Spatial variability of soil chemical properties under different land-uses in Northwest Ethiopia.

The understanding of the spatial variation of soil chemical properties is critical in agriculture and the environment. To assess the spatial variability of soil chemical properties in the Fogera plain, Ethiopia, we used Inverse Distance Weighting (IDW), pair-wise comparisons, descriptive analysis, and principal component analysis (PCA). In 2019, soil samples were collected at topsoil (a soil depth of 0-20 cm) from three representative land-uses (cropland, plantation forestland, and grazing lands) using a grid-sampling design. The variance analysis for soil pH, available phosphorus (avP), organic carbon (OC), total nitrogen (TN), electrical conductivity (EC), exchangeable potassium (exchK), exchangeable calcium (exchCa), and cation exchange capacity (CEC) revealed significant differences among the land-uses. The highest mean values of pH (8.9), avP (32.99 ppm), OC (4.82%), TN (0.39%), EC (2.28 dS m-1), and exchK (2.89 cmol (+) kg-1) were determined under grazing land. The lowest pH (6.2), OC (2.3%), TN (0.15%), and EC (0.11 dS m-1) were recorded in cultivated land. The PCA result revealed that the land-use change was responsible for most soil chemical properties, accounting for 93.32%. Soil maps can help identify the nutrient status, update management options, and increase productivity and profit. The expansion of cultivated lands resulted in a significant decrease in soil organic matter. Thus, soil management strategies should be tailored to replenish the soil nutrient content while maintaining agricultural productivity in the Fogera plain.

Introduction

Environmental degradation caused by irrelevant land-use is a global problem in sustainable agriculture. Land-use change markedly affects soil properties [1,2]. Changing land-use frpan class="Gene">om forest cover to plough-land may result in a decrease in soil fertility, nutrients, and thus productivity [3-6], as well as increased soil perturbation [5,7-12].

Rapid population growth and environmental factors in Ethiopia have resulted in converting forestland and grassland to cultivated land [13]. The expansion of cultivated areas has a substantial influence on soil nutrient content [14]. [15] reported changes in the amount of soil pan class="Chemical">organic carbon and total N due to changes in land-use and land-cover in the Gerado catchment, northeastern Ethiopn>ia. [16] also reported that deforestation has led to the deterioration of soil organic matter. As a result, soil nutrient pan class="Disease">deficiency is a critical problem in the country and a major crop production constraint [17,18].

Ethiopia has seen an increase in cultivated lands and eucalyptus plantations and decreased grazing lands because of population growth [13]. The eucalyptus plantation had a significant impact on soil properties [19-21]. [22] reported a reduction in soil organic carbon (OC), total nitrogen (TN), exchangeable cations, and cation exchange capacity (CEC) owing to the shift from woodlands to croplands and grazing lands in the same country. [23] also found a decline in pH and soil organic matter content in cultivated land in Ethiopia’s Kabe watershed. As a result, scientific records of spatial variability and distribution of soil properties among land-use shifts are critical for optimizing fertilizer use and increasing crop productivity [20].

In developing countries, including Ethiopia, land-use/land-cover change is a significant source of greenhouse gases (GHGs) such as carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) emissions [24]. Furthermore, nitrogen-containing fertilizers [25,26], tillage [26], and complete removal of vegetation and residues [27] have influenced spatial variability, soil nutrient cycling, and GHGs emission. Thus, information on the spatial variability of soil due to land-use change is critical in this regard.

Accurate and scientific information about soils is essential for developn>ing effective soil management techniques that sustain agricultural production while maintaining environmental quality. Furthermore, site-specific management of pH, organic carbon, available N, available P, and available K [28] improves input use efficiency [29], increases crop production economic returns, and reduces ecological risks [30].

Many repan class="Gene">searchers have recently used geostatistics to estimate the spatial variability of soil propn>erties [31-34]. In geostatistics, the inverse distance weighting (IDW) model can be used to map the spatial distribution of any soil propn>erty measured for spatially distributed samples [35]. Understanding the spatial variability of soil propn>erties [36] and developn>ing site-specific recpan class="Gene">ommendations [36,37] are critical for optimizing nutrient usage, improving crop performance, and minimizing environmental risks [38].

Furthermore, the spatial information produced using geostatistical techniques would be an input to improve food security and obtain sustainable yield in developing countries, including Ethiopia, which has never been thoroughly investigated using spatial prediction models [39]. Understanding of different land’s soil fertility of various land-use types could be used to predict, monitor, and evaluate the effects of changes in land-use types on soil properties, scheming appropriate land-use planning, and sustaining agricultural productivity. In this regard, previous researches on Fogera plain area have not yet adequately discussed the Fogera plain area. Thus, the target of this research paper was to assess the effects of land-use types on spatial variability and distribution of soil fertility qualities, such as pH, organic carbon (OC), total nitrogen (TN), available phosphorus (avP), exchangeable calcium (Ca2+), exchangeable potassium (K+), electrical conductivity (EC), and cation exchange capacity (CEC) in Fogera plain, the highland of Ethiopia.

Materials and methods

Description of the study area

The research was conducted in the Fogera plain area (37° 0′ 0" E - 38° 45′ 0" E and 11° 15′ 0" N-12° 15′ 0" N) in the northwest highland of Amhara region, Ethiopn>ia (Fig 1). It has a total area of 5,646 hectares. The topn>ography of the study area is flat land. Rice (Oryza sativa L.), maize (Zea mays L.), and Teff [Eragrostis tef (Zucc.)] are the main crops grown in the study region. Rice production (76%) is primarily a subsistence farming operation in the study area. Crop residues are collected for use as fuelwood or animal feed. As a result, no crop residue remains in the field to serve as a source of organic amendments. Rice, onions, and eucalyptus products are essential sources of income for the local people.

Fig 1

The study area’s location: (a) Ethiopia, (b) Amhara region, and (c) soil sampling.

Sources of spatial data and their extraction

The study area’s land-use/land-covers for 2019 was derived from an Ethiopn>ia Mapping Agency (EMA) 1:20,000 scale land-use/land-cover map, and the mainland-use system consisted of cropn>land (4,362.73 ha, 77.27%), plantation forestland (6,96.29 ha, 12.33%) and grassland (586.98 ha, 10.39%). We also performed reconnaissance surveys from August to November/2019 to validate the map. Using ArcGIS software version 10.5, a digital elevation model (ASTER DEM) with a resolution of 20 * 20 m, downloaded from the EMA website [40], was used to generate elevation and slope of the study area.

As shown Figs 2 and 3, agroecology belonging to Kolla (<1800 m a.s.l.), Weyna dega (1,800–2,400 m a.s.l.), and dega (>2400 m a.s.l.) has an area share of 16.24%, 71.93%, and 11.83%, respectively. According to the digital soil map obtained from Water and Land Resource Centre (WLRC), the soil types in the Fogera plain region are Chromic Vertisols (48.57%), Eutric Nitosols (17.65%), Orthic Luvisols (15.75%), Eutric Cambisols (10.78%), Chromic Luvisols (3.97%), and Lithosols (3.27%) [41].

Fig 2

Land-use of the area: (d) Eucalyptus plantation forestland, (e) Cultivated land, and (f) Grazing land.

Fig 3

Different maps of the study area, particularly (g) Soil types, (h) Altitude, and (i) Slope.

Soil sampling, laboratory analysis, and statistical analysis

We used the fishnet tool included with ArcGIS software version 10.5 to build a regularly spaced grid of sampling points on the land-uses in the study region. Following that, 60 representative soil samples (20 from each land use: cropn>land, plantation forestland, and grazing land) were identified at topn>soil (a depth of 0–20 cm) in February-April/2020 using a systematic purposive approach. The topsoil was chosen as plants and soil management practices most influence it. To record each grid center in the field and the latitudes, longitudes, and elevations of sampling points, a portable Global Positioning System (Garmin 60; 2 m accuracy) was used. Soil sampling locations were chosen to reflect each land-use condition by taking topographic features and soil conditions into account [42]. Each soil sample was created by compositing five sub-samples, improving sampling intensity and lowering soil analysis costs [43,44]. A kilogram of soil sample was collected from each location, air-dried, ground using a mortar and pestle, and analyzed at the Amhara Regional Soil Laboratory Center following national standard research methods [45].

Soil pH was measured potentiometrically in H2O at the soil to solution ratio (1: 2.5) using a combined glass electrode pH meter (Model CP-505, Zabrze ul, Poland) [46]. The electrical conductivity (EC) of the soil was determined using an EC meter at the soil to water ratio of 1: 5 (Orion Model 145, USA) [47]. The Walkley-Black procedures were used to measure soil organic carbon (OC). A weighed portion (1–2 gm) of the dried, ground soil samples were treated with 5 ml of 0.4 N potassium dichromate solution (K2Cr2O7) followed by the addition of 10 ml of concentrated sulfuric acid. The mixture was gently mixed and left for 16–18 hours before being given 100 ml of triple-distilled water. The excess of dichromate was back-titrated with the standard 0.2 N ferrous ammonium sulfate solution. The acidic dichromate was blankly titrated with ferrous ammonium sulfate solution [45,48].

The total nitrogen (TN) of the soils was determined through digestion, distillation, and titration procedures of the Kjeldahl using the Kjeldahl apparatus (Gallenhamp, USA) [49]. The soil’s available phosphorus (avP) was measured using 0.5 M NaHCO3, pH of 8.5, a soil to solution ratio of 1: 20 for half an hour. The (avP) was extracted with 1 M ammonium chloride, 0.5 M ammonium fluoride, 0.1 M sodium hydro-oxide (from Blulux Laboratory Reagent (p) Ltd), and the amount was measured using a spectrophotometer (UV1700, Japan) [50,51]. Exchangeable calcium (Ca), magnesium (Mg), potassium (K), and sodium (Na) were determined by saturating the soil samples with 1 M ammonium acetate solution at pH 7.0. Subsequently, Ca and Mg were determined using Perkin-Elmer Model 290 atomic absorption spectrophotometer (ColVisTec, Germany); while exchangeable Na and K were measured using a Model 18 Perkin-Elmer flame photometer [52].

The soil’s cation exchange capacity (CEC) was calculated by replacing NH4+ saturated samples with K+ from a percolated KCl solution (from LOBA CHEMIE PVT.LTD). Washing with ethanol (from LOBA CHEMIE PVT.LTD) eliminated excess salt, and NH4+ was displaced by K+ [53]. Merck KGaA and Sigma-Aldrich, Steinheim, Germany supplied all of the chemicals and reagents, such as potassium dichromate, sulphuric acid, ferrous sulfate, ferroin, sodium bicarbonate, ammonium chloride, ammonium fluoride, and ammonium acetate, unless otherwise mentioned.

The variation of soil organic carbon, total nitrogen, and potassium was defined using the Inverse Distance Weighting (IDW) model [54,55]. Furthermore, IDW has been widely used by scholars for the prediction of soil OM and soil nitrate [56], P and K levels [57], and soil pH scale [58]. The current study used IDW to map the spatial distribution of the soil chemical properties under the ArcGIS environment. Besides, pair-wise comparisons, descriptive analysis, and principal component analysis (PCA) were performed using Statistical Analyses System (SAS) software version 9.4 and the Statistical Package for Social Sciences (SPSS) software version 24, respectively. Means were compared through the Tukey test at 1% probability.

Ethics statement

Debre Tabor University’s Research and Publication Directorate and Bahir Dar University’s Research and Publication Directorate authorized the present study to collect soil samples and access the field site. Farmers agreed to collect the soil samples in the study area, as the survey has no harmful effects on humans.

Results and discussion

Effect of land-use/land-cover types on soil fertility quality

Soil pHH2O

The soil pH, which affects nutrient availability, varied significantly (P < 0.05) depending on land-use type (Table 1). The soil pH values were found to be the highest (8.9) and the lowest (6.2) under the grazing and the cultivated lands, respectively (S2 Table and Figs 4 and 5). According to [59], higher soil pH levels obtained from plantation forestland and grazing land could be associated with the presence of basic cations emanated from weathering [23] and the potash obtained from ashes [60].

Table 1

Soil pHH2O rating, area share (ha, %) by land-use, and parametric test.

Common name	pH rating	Area share (ha, %) by land-use
		Cropland		Plantation forestland		Grazing land
		Area (ha)	%	Area (ha)	%	Area (ha)	%
Moderately acid	5.6–6.5	181.84	4.17	1.11	0.16	9.50	1.62
Neutral	6.6–7.3	1,576.93	36.15	139.05	19.97	173.04	29.48
Moderately alkaline	7.4–8.4	2,603.96	59.69	556.12	79.87	404.44	68.90
Total		4,362.73	100	696.29	100	586.98	100
pH (mean ± standard error)		6.58 ± 0.05 a		7.40 ± 0.05 b		8.44 ± 0.05 c

Means of pH with different letters are significantly varied (Tukey, p < 0.01).

Fig 4

Maps of (n) Soil pH, (o) Organic carbon, (p) Total nitrogen, and (q) Available phosphorus.

Fig 5

Mean values of soil parameters using box plots.

Means of pan class="Gene">pH with different letters are significantly varied (Tukey, p < 0.01).

Available phosphorus (avP)

The analysis of variance showed a significant difference in the mean value of avP among land-use types. Following the limit established by [61], very high (>20 ppm) avP content was observed in soils of all land-uses (Table 2 and Fig 4). Higher avP values in soils could be revealed by the recurrent use of mineralized phosphorus [38], and the addition of manure, compost, and ashes [62], presence of weathered soil minerals [63], and actions of microbes. Higher levels of avP in the soils indicate that the soils have optimum nutrients for crop growth. [22,64] reported similar findings in Ethiopia. However, regular monitoring of the availability of phosphorus in the soil is essential.

Table 2

Soil available phosphorus (avP) rating, area share (ha, %) by land-use, and parametric test.

Common name	AvPrate	Area share (%) by land-use
		Cropland		Plantation forestland		Grazing land
	ppm	Area (ha)	Area (%)	Area (ha)	Area (%)	Area (ha)	Area (%)
Medium	11–14	273.66	6.27	35.02	5.03	23.05	3.93
High	15–20	1,425.74	32.68	200.90	28.85	118.12	20.12
Very high	>20	2,663.33	61.05	460.37	66.12	445.82	75.95
Total		4,362.73	100	696.29	100	586.98	100
AvP (mean ± standard error)		21.32 ± 0.12 a		11.43± 0.06 b		32.52± 0.06 c

Means of available P with different letters are significantly different (Tukey, p < 0.01).

Means of available pan class="Chemical">P with different letters are significantly different (Tukey, p < 0.01).

Soil organic carbon (OC) and total nitrogen (TN)

Land-use changes caused a significant difference in soil organic carbon (OC) and total nitrogen (TN). According to the ranking set by [65], low organic carbon content (2.44%) in the soils dominated the agricultural land (87.66%), grazing land (81.7%), and eucalyptus plantation forestland (80.63%), as shown in Table 3 and Figs 4 and 5. The highest (4.35%) and lowest (2.44%) OC contents obtained in grazing and croplands demonstrated that soil OC showed a better response to land-use type. The variations in the mean value of soil organic carbon and total nitrogen could have attributed to high erosion rates, crop residue exclusion, increased mineralization rates, and nutrient deficiency [38,66]. The higher organic carbon and available P contents of the grazing lands suggest that OM is the primary source of avP [67].

Table 3

Soil organic carbon (OC) rating, area share (ha, %) by land-use, and parametric test.

Common name	OC rate	Area share (ha, %) by land-use
		Cropland		Plantation forestland		Grazing land
	%	Area (ha)	Area (%)	Area (ha)	Area (%)	Area (ha)	Area (%)
Low	2–4	3,824.5	87.66	561.44	80.63	479.59	81.70
Medium	4–8	538.23	12.34	134.85	19.37	107.40	18.30
Total		4,362.73	100	696.29	100	586.98	100
OC (mean ± standard error)		2.44 ± 0.02 a		3.43 ± 0.06 b		4.35± 0.06 c

Means of soil OC with different letters are significantly different (Tukey, p < 0.01).

Means of soil pan class="Chemical">OC with different letters are significantly different (Tukey, p < 0.01).

According to the rate of [61], the cropland and plantation forestland demonstrated, respectively, low (0.17%) and high total nitrogen (0.35%) contents in the soils (Table 4 and Figs 4 and 5). In line with this, cropn>lands had lower soil OC content [2,23,68]. Higher soil OC and TN contents found in plantation forests and grazing lands are most likely due to grass burning and dung deposition, respectively. Furthermore, researchers have advocated for grazing to sustain nutrient cycling and decomposition rates [69]. The low total nitrogen content may be eligible to minimize nitrogen loss by volatilization or leaching and rapid decomposition of OM. Hence, grassland and eucalyptus plantation conversion to cultivated land worsens soil OC and TN decline [70]. Thus, for long-term development, the soils need external nitrogen and carbon inputs.

Table 4

Soil total nitrogen (TN) rating, area share (ha, %) by land-use, and parametric test.

Common name	TN rate	Area share (ha, %) by land-use
		Cropland		Plantation forestland		Grazing land
	%	Area (ha)	Area (%)	Area (ha)	Area (%)	Area (ha)	Area (%)
Low	0.1–0.2	1,219.37	27.95	69.66	16.29	115.14	19.62
Medium	0.2–0.3	2,159.42	49.50	62.31	14.57	244.65	41.68
High	0.3–0.4	983.94	22.55	295.63	69.14	227.18	38.70
Total		4,362.73	100	427.60	100	586.98	100
TN (mean ± standard error)		0.17 ± 0.0 a		0.27 ± 0.01 b		0.35± 0.0 c

Means of TN with different letters are significantly different (Tukey, p < 0.01).

Means of pan class="Gene">TN with different letters are significantly different (Tukey, p < 0.01).

Exchangeable cations (K, Ca) and electrical conductivity (EC)

Next to nitrogen and phosphorus, potassium is the third most important essential element that limits crop productivity. As shown in Tables 5 and 6 and Figs 5 and 6, there was a significant variation in soil K, Ca, and EC contents based on land-use. Besides, according to [59,61], the soils in the study region had high Ca (>20 cmol(+) kg−1) and K (0.51–1.51 cmol(+) kg−1) contents. In the soils, higher Ca and K levels were found. It might be due to the type of parent materials, weathering, land-use types, fertilizer types, and leaching rates, crop remains, and litter fall [71]. The higher Ca and K contents present in grazing and plantation forestlands are associated with the higher pH value [72] and clay particles [73]. On the other hand, the soils showed slightly salty.

Table 5

Soil exchangeable potassium (exchK) rating, area share (ha, %) by land-use, and parametric test.

Common name	ExchK (rate)	Area share (ha, %) by land-use
		Cropland		Plantation forestland		Grazing land
	cmol(+) kg−1	Area (ha)	Area (%)	Area (%)	Area (ha)	Area (%)	Area (ha)
High	0.51–1.51	2,609.17	59.81	320.17	45.98	257.26	43.83
Medium	1.51–2.3	1,733.37	39.73	373.31	53.61	326.57	55.64
Very high	>2.3	20.19	0.46	2.80	0.40	3.15	0.54
Total		4,362.73	100	696.29	100	586.98	100
ExchK (mean ± standard error)		0.87± 0.01 a		1.47 ± 0.08 b		1.81 ± 0.08 c

Means of exchK with different letters are significantly different (Tukey, p < 0.01).

Table 6

Electrical conductivity (EC) rating, area share (ha, %) by land-use, and parametric test.

Common name	EC rate	Area share (ha, %) by land-use
		Cropland		Plantation forestland		Grazing land
	dS m−1	Area (ha)	Area (%)	Area (ha)	Area (%)	Area (ha)	Area (%)
Not salty	<0.75	1,427.14	32.71	96.07	13.80	146.18	24.90
Slightly salty	0.75–2	2,660.19	60.98	538.15	77.29	372.90	63.53
Moderately salty	2–4	275.30	6.31	62.07	8.91	67.90	11.57
Sum		4,362.63	100	696.29	100	586.98	100
EC (mean ± standard error)		0.13± 0.0 a		1.21 ± 0.01 b		2.22± 0.01 c

Means of EC with different letters are significantly different (Tukey, p < 0.01).

Fig 6

Maps: (r) Exchangeable calcium, (s) Exchangeable potassium, (t) Electrical conductivity, and (u) Cation exchange capacity.

This result suggests that Ca and K do not appear to be limiting nutrients to crop production in the region. Based on the EC rate established by [74], no significant amounts of soluble pan class="Chemical">salts were accumulated, implying that plant growth and developn>ment would be unaffected.

Cation Exchange Capacity (CEC)

According to the rate set by [61], a significant variance and higher CEC indicated that soils in the study area have a high capacity to retain nutrients against leaching losses (Table 7 and Fig 6). The highest CEC values recorded in cultivated land-use may be soil organic material, pan class="Gene">pH, quantity, and typn>e of clay, which adsorb and retain positive cations through electrostatic force [75]. The current findings were also consistent with [76-78], who reported higher CEC under cultivated lands in Ethiopn>ia’s highlands.

Table 7

Cation exchange capacity (CEC) rating, area share (ha, %) by land-use, and parametric test.

Common name	CEC (rate)	Area share (ha, %) by land-use
		Cultivated land		Plantation forestland		Grazing land
	cmol(+) kg−1	Area (ha)	Area (%)	Area (ha)	Area (%)	Area (ha)	Area (%)
High	15–30	1,402.31	32.14	357.07	51.28	275.72	46.97
Very high	>30	2,960.42	67.86	339.22	48.72	311.26	53.03
Sum		4,362.73	100	696.29	100	586.98	100
CEC (mean ± standard error)		40.36 ± 0.10 a		31.53± 0.06 b		25.24 ± 0.06 c

Means of CEC with different letters are significantly different (Tukey, p < 0.01).

Principal component analysis (PCA) of soil chemical properties

The first two principal component analyses (PCA) with eigenvalues greater than one were able to explain the most significant variance (93.32%) of the analyzed soil chemical properties (S1 Fig) [79]. Moreover, 76.77% of the variation in data was explained by pH, organic carbon (OC), total nitrogen (TN), exchangeable potassium (exchK), electrical conductivity (EC), and cation exchange capacity (CEC) on the first PC. Simultaneously, the second component notably loaded the available phosphorus (avP) and exchangeable calcium (exchCa) (Table 8 and S1 Fig). The communality is the proportion of the variation of a variable retained in a component. The communalities of the two PCs explained by each soil variable ranged from 73 to 99%. In PC 1, CEC showed a higher loading value (-1.0) and communality (99%) and is called ‘cation exchange capacity, CEC factor.’ While in PC 2, available phosphorus showed a higher loading value (0.86) and communality (98%) and termed ‘available phosphorus, avP factor.’ It indicates that the PCA reduces the dimensions and complexity of the soil data matrix [80].

Table 8

Principal component analysis of soil chemical properties about land-uses in Fogera plain, northwest Ethiopia.

Principal component	PC1	PC2
Eigenvalue	6.07	1.29
Variance (%)	79.97	18.58
Variables	Eigenvectors		Communalities
pH	0.96	0.12	0.94
Available phosphorus	0.48	0.86	0.98
Organic carbon	0.96	0.03	0.98
Total nitrogen	0.96	0.00	0.73
Exchangeable potassium	0.81	-0.08	0.98
Exchangeable calcium	-0.67	0.73	0.93
Electrical conductivity	0.99	0.03	0.93
Cation exchange capacity	-1.00	0.04	0.99

Bold eigenvector values referred to highly weighted variables in the PC.

Implications for sustainable soil fertility management and environmental conservation

Our results showed that the transition from grassland to cultivated land and eucalyptus plantation significantly reduced the total nitrogen within Fogera plain’s topsoil. Organic materials may increase the nitrogen content in the soil, which has a more significant effect on crop growth and yield than other nutrients. Nevertheless, avP range of the area’s soils was high (>20 ppm), which could be attributed to the frequent use of mineralized phosphorus [38]. The addition of nitrogen-containing fertilizer inputs might also improve the cultivated lands’ soil nutrient supply to better crop yield and farming profitability. However, the overuse of nitrogen and phosphorus fertilizer may lead to global climate change due to their energy-intensive processing and inefficient use [81], eutrophication of water bodies [82], and soil acidification [83]. Besides, total greenhouse gas emissions, including N2O, CO2 have increased under cultivated lands, depending on the decomposition of organic materials in the soil [81]. Soil management methods, optimum N application rate [84], organic resources, and nitrification inhibitors are all possible soil management approaches.

The spatial soil variability across land-uses is vital for sustainable land management practices, reducing soil erosion, enhancing land productivity, improving farmers’ livelihood, reducing GHGs, and maintaining environmental quality [85,86]. Furthermore, we should develop relevant land-use planning and policies to provide an optimal solution geared toward improving the soil’s nutrient use efficiency and reducing the adverse environmental effects, including nitrate losses to water and N2O emissions [87,88].

Conclusion

The soil pH, available phosphorus (avP), organic carbon (OC), total nitrogen (TN), electrical conductivity (EC), exchangeable bases (Ca and K), and cation exchange capacity (CEC) were varied among land-use types in the Fogera plain. Grazing land had the highest values of pH (8.9), avP (32.99 ppm), OC (4.82%), TN (0.39%), EC (2.28 dS m−1), and exchK (2.89 cmol(+) kg-1), while in cultivated land had the lowest OC (2.3%), TN (0.15%), soil pH (6.2), and EC (0.11 dS m−1). The difference in the land-use types could be associated with the variation of soil chemical properties in the study area.

The study found that the expansion of cultivated lands depleted soil OC and TN, restricting crop growth and decreasing crop yield. Thus, proper nutrient management strategies, such as adding organic and inorganic materials, should be adopted, especially for these nutrients. Besides, PCA prioritized the CEC and avP as the most critical soil chemical properties across land-use types in the study area. Priority should also be given to these selected variables as they provide reliable and on-time information about soil chemical properties and nutrient contents under study area conditions.

Moreover, soil properties’ maps improve soil management alternatives, optimize fertilizer use, and enhance crop productivity, thus contributing to the nation’s food security. Models should gear to larger samples in future studies to understand better the spatial variability of soil properties of the Fogera plain, Ethiopia.

Loading plot (y) and scree plot (z).

Organic carbon (OC), Total nitrogen (TN) Available phosphorus (avP), Exchangeable calcium (ExchCa), Exchangeable potassium (ExchK), Cation exchange capacity (CEC), and Electrical conductivity (EC).

(TIF)

Click here for additional data file.

Q-Q plots of soil fertility parameters in Fogera plain.

pH, Cation exchange capacity (CEC), Organic carbon (OC), and Total nitrogen (TN).

(TIF)

Click here for additional data file.

Laboratory results of soil chemical properties in Fogera plain.

(XLS)

Click here for additional data file.

Descriptive statistics of soil chemical properties in Fogera plain.

(XLS)

Click here for additional data file.

26 Mar 2021

pan class="Chemical">PONE-D-21-03433

Spatial variability of soil properties under different land-uses in Northwest Ethiopia

PLOS ONE

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Remigio Paradelo Núñez

Academic Editor

PLOS ONE

Journal Requirements:

When submitting your revision, we need you to address these additional requirements.

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at and

2. pan class="Chemical">Please include a separate caption for each figure in your manuscript.

3. pan class="Chemical">Please ensure that you refer to Figures 5 and 6 in your text as, if accepted, production will need this reference to link the reader to the figure.

4. pan class="Chemical">Please include captions for your Supporting Information files at the end of your manuscript, and update any in-text citations to match accordingly. pan class="Chemical">Please see our Supporting Information guidelines for more information: http://journals.plos.org/plosone/s/supporting-information.

Additional Editor Cpan class="Gene">omments (if provided):

[Note: HTML markup is below. pan class="Chemical">Please do not edit.]

Reviewers' cpan class="Gene">omments:

Reviewer's Responses to Questions

Cpan class="Gene">omments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific repan class="Gene">search with data that supports the conclusions. Expn>eriments must have been conducted rigorously, with appropn>riate controls, replication, and sample sizes. The conclusions must be drawn appropn>riately based on the data presented.

Reviewer #1: No

Reviewer #2: Partly

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: No

Reviewer #2: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copn>yedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typn>ographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: No

Reviewer #2: Yes

**********

5. Review Cpan class="Gene">omments to the Author

Please use the space provided to expn>lain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The manuscript “Spatial variability of soil properties under different land-uses in Northwest Ethiopia" is well written. In my opinion, the manuscript is relevant and appropriate for the pan class="Chemical">PlosONE journal. Nonetheless, I have the following suggestions that should be addressed by the authors before to publish:

Title: please add ‘chemical’ in title

[Not a cpan class="Gene">omment, but you have not defined paragrapan class="Gene">ph sign meaning in author name list- double check]

L#21-23: these are not only prpan class="Chemical">ocedure to evaluate soil variability, so please make a general sentence but fpan class="Chemical">ocus as background information or rationale of the study

pan class="Gene">L#24: Include depth of topn>soil

Abstract is poorly written. No clear explanation of measured variables. What was the tool(s) used to explore spatial variability of study area? Only descriptive statistics?

pan class="Gene">L#38: what do you mean by inappropn>riate?

L#43: please double check your citation style for [14] based on journal guidelines

L#58-61: Besides scholars, your study should be valuable to farmers as well. Please think about other site-specific recommendation practices and mention it in Introduction section because there is not only geostatistics for optimizing nutrient use and improve crop production. Countries like, Nigeria, India, Nepal have used soil testing mobile van as well. I am not sure about similar approach in Ethiopia, but it is suggested to visit this link (https://doi.org/10.1080/15427528.2017.1387837) for more information.

L#111: Is this correct amount? 20-50 pan class="Chemical">mg of dried soil; please cross-check with this information: https://www.environment.nsw.gov.au/resources/soils/testmethods/pan class="Chemical">oc.pdf

L#136-139: why there is not any information pan class="Gene">about tools of spatial interpn>olation in Introduction section? You need to re-structure your Introduction and Methodology (statistical analysis) sections.

No justification- why did you select IDW only, why not others?

Results: there is repetition of information (results) in table and text many times. Also there is no any value of Table 8, just include mean and SE, and then lsd cpan class="Gene">omparison. If you have this already, then delete Table 8.

L#251-252: How GHG information relates to your current study? Do not bring larger picture in your Discussion section. pan class="Chemical">Please fpan class="Chemical">ocus on that what you have done and its implications.

L#255: what is best land planning?

Good luck!

Reviewer #2: The authors presented a work on "Spatial variability of soil properties under different land-uses in Northwest Ethiopia" but however dwelt so much on land use instead of the spatial variability. The authors use only 60 samples to produce the map of the distribution of soil chemical properties in the study lpan class="Chemical">ocation of more than 6,000 ha. This to me is not acceptable because the samples are too few to highlight the spatial variability in the soil propn>erties. Even the map produced was not mentioned in the abstract let alone discussing them in the results and Discussion section. A number of information that is supposed to be in the abstract are missing. There were a lot of long sentences that need to be summarized or broken into two or more sentences.

**********

6. pan class="Chemical">PLOS authors have the opn>tion to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Submitted filename: pan class="Chemical">PONE-D-21-03433_reviewer.pdf

Click here for additional data file.

27 pan class="Gene">Apr 2021

Date: pan class="Gene">April 24 09, 2021

Rebuttal letter

pan class="Chemical">PONE-D-21-03433

We are glad about the academic editor and the reviewers’ comments, which strengthen the current version of the manuscript “Spatial variability of soil properties under different land-uses in Northwest Ethiopia”. In addition, our utmost sincere gratitude goes to you and the reviewers who devote their valuable time to bring our manuscript to a qualified paper.

We have provided a one by one reply to all concerns and cpan class="Gene">omments given below. We thank you for your consideration of this resubmission and look forward to your response.

Best regards,

Gizachew Ayalew Tiruneh (on behalf of all co-authors)

Lecturer in Debre Tpan class="Gene">abor University

pan class="Gene">Ph.D. Fellow in soil science, Bahir Dar University

Email: tiruneh1972@gmail.cpan class="Gene">om

Editor’s cpan class="Gene">omments

Cpan class="Gene">omments 1: A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.

Response: We addressed the concerns provided by the editor and reviewers and uploaded a file labeled “Response to Reviewers”.

Cpan class="Gene">omments 2: A marked-up copn>y of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.

Response: We tried to do it.

Cpan class="Gene">omments 3: An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

Response: We have addressed accordingly.

Cpan class="Gene">omments 4: If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter.

Response: We have not made any changes to financial disclosure.

Cpan class="Gene">omments 5: Guidelines for resubmitting your figure files are available below the reviewer cpan class="Gene">omments at the end of this letter.

Response: We made corrections as per the guidelines

Comments 6: If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

Response: The majority of our protocols involve standard methods such as soil pH, available phosphorus (av. P), organic carbon (OC), total nitrogen (TN), electrical conductivity (EC), exchangeable Ca, and K, and cation exchange capacity (CEC) measurement. We have specified our Lab protocol in the revised manuscript [reference #45].

Comments 7: When submitting your revision, we need you to address these additional requirements, please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at

https://journals.plos.org/plosone/s/file?id=wjVg/pan class="Chemical">PLOSOne_formatting_sample_main_body.pdf and https://journals.plos.org/plosone/s/file?id=ba62/pan class="Chemical">PLOSOne_formatting_sample_title_authors_affiliations.pdf

Response: We addressed pan class="Chemical">PLOS ONE's style requirements in this revision.

Comments 8: Please include a separate caption for each figure in your manuscript.

Response: We addressed pan class="Chemical">PLOS ONE's style requirements in this revision using pan class="Chemical">PACE.

Cpan class="Gene">omments 9: pan class="Chemical">Please ensure that you refer to Figures 5 and 6 in your text as, if accepted, production will need this reference to link the reader to the figure.

Response: We cited the figures in manuscript’s text.

Cpan class="Gene">omments 10: pan class="Chemical">Please include captions for your Supporting Information files at the end of your manuscript, and update any in-text citations to match accordingly.

Response: We followed pan class="Chemical">PLOS ONE's Supporting Information guidelines to include the captions.

Reviewers' cpan class="Gene">omments:

Reviewer #1:

Cpan class="Gene">omments 1: 1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific repan class="Gene">search with data that supports the conclusions. Expn>eriments must have been conducted rigorously, with appropn>riate controls, replication, and sample sizes. The conclusions must be drawn appropn>riately based on the data presented.

Reviewer #1: No

Reviewer #2: Partly

Response: Dear Reviewers, thank you so much for taking your valuable time to elevate the quality of our manuscript. We do hope that the Reviewer’s concerns will be addressed.

________________________________________

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: No

Reviewer #2: Yes

Response: Thank you. We have gone thoroughly the revised manuscript, and hopefully that the first Reviewer will be satisfied.

________________________________________

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

Thank you.

________________________________________

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copn>yedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typn>ographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: No

Reviewer #2: Yes

Response: Thank you. We have thoroughly revised our manuscript with the help of Grammarly (premium) and Turnitin software, and we do hope that the first Reviewer’s concerns will be addressed.

________________________________________

5. Review Cpan class="Gene">omments to the Author

Reviewer #1:

The manuscript “Spatial variability of soil properties under different land-uses in Northwest Ethiopia" is well written. In my opinion, the manuscript is relevant and appropriate for the pan class="Chemical">PlosONE journal. Nonetheless, I have the following suggestions that should be addressed by the authors before to publish:

Title: please add ‘chemical’ in title

[Not a cpan class="Gene">omment, but you have not defined paragrapan class="Gene">ph sign meaning in author name list- double check]

Response: Thank you. We have tried to add ‘chemical’ the title in the way this reviewer has suggested.

L#21-23: these are not only prpan class="Chemical">ocedure to evaluate soil variability, so please make a general sentence but fpan class="Chemical">ocus as background information or rationale of the study

Response: Thank you. We have revised the background information or rationale of the study.

pan class="Gene">L#24: Include depth of topn>soil

Abstract is poorly written. No clear explanation of measured variables. What was the tool(s) used to explore spatial variability of study area? Only descriptive statistics?

Response: Thank you. We have included depth of topsoil (0-20 cm) and have revised the Abstract section. We also incorporated more ideas on geo-statistical (IDW) tool and others (ANOVA, box plots, and pan class="Chemical">PCA). We hopn>e that this revised version will be satisfying.

pan class="Gene">L#38: what do you mean by inappropn>riate?

Response: Thank you. We replaced “inappropriate” by “irrelevant” as shown in [L43] of the revised manuscript.

L#43: please double check your citation style for [14] based on journal guidelines

Response: Thank you. The reference style is now made consistent, reference # 14 (in the revised manuscript) with others.

L#58-61: Besides scholars, your study should be valuable to farmers as well. Please think about other site-specific recommendation practices and mention it in Introduction section because there is not only geostatistics for optimizing nutrient use and improve crop production. Countries like, Nigeria, India, Nepal have used soil testing mobile van as well. I am not sure about similar approach in Ethiopia, but it is suggested to visit this link (https://doi.org/10.1080/15427528.2017.1387837) for more information.

Response: Thank you. We appreciate your valuable recommendation and thank for showing this important link. We mentioned some site-specific recommendation practices and included in Introduction section. However, Ethiopia has not yet used mobile van so far for soil testing like the above-mentioned countries.

L#111: Is this correct amount? 20-50 pan class="Chemical">mg of dried soil; please cross-check with this information:

https://www.environment.nsw.gov.au/resources/soils/testmethods/pan class="Chemical">oc.pdf

Response: Thank you for indicating this useful source. We have added a relevant source [reference # 45] to get more elpan class="Gene">aboration on the idea of “the amount of dried soil required in examining pan class="Chemical">OC [L145 in the revised manuscript].

L#136-139: Why there is not any information pan class="Gene">about tools of spatial interpn>olation in Introduction section? You need to re-structure your Introduction and Methodology (statistical analysis) sections.

No justification- why did you select IDW only, why not others?

Results: there is repetition of information (results) in table and text many times. Also there is no any value of Table 8, just include mean and SE, and then lsd cpan class="Gene">omparison. If you have this already, then delete Table 8.

Response: Thank you for the suggestion. We share with your concerns. We tried to incorporate information pan class="Gene">about tools of spatial interpn>olation in Introduction section. We also re-structured the Introduction and Methodology (statistical analysis) sections. The justification of IDW selection was included in Introduction section and Methodology section. The repetition of information (results) in table and text were minimized and Table 8 was removed.

L#251-252: How GHG information relates to your current study? Do not bring larger picture in your Discussion section. pan class="Chemical">Please fpan class="Chemical">ocus on that what you have done and its implications.

Response: Thank you for the concern. We added span class="Gene">ome relevant ideas of GHGs and its implications in Abstract, Introduction, Discussion, and Conclusion sections.

L#255: what is best land planning?

Response: Thank you for the comment. We replaced “relevant” instead of “best” in the phrase “best land planning” (L296). A relevant land-use planning gives time and resources to decision-making processes in order to reach conclusions on suitable or best possible use of land based on long-term objectives and benefits that are more equitable.

Reviewer #2:

The authors presented a work on "Spatial variability of soil properties under different land-uses in Northwest Ethiopia" but however dwelt so much on land use instead of the spatial variability. The authors use only 60 samples to produce the map of the distribution of soil chemical properties in the study lpan class="Chemical">ocation of more than 6,000 ha. This to me is not acceptable because the samples are too few to highlight the spatial variability in the soil propn>erties. Even the map produced was not mentioned in the abstract let alone discussing them in the results and Discussion section. A number of information that is supposed to be in the abstract are missing. There were a lot of long sentences that need to be summarized or broken into two or more sentences.

Response: Thank you for the concern. In considering the soil variability, cpan class="Gene">omposite and purpn>osive soil sampling was employed to reduce sampling intensity. Moreover, most coverage of the study area is gentle slopn>e, bordering Lake Tana. Supportive references were also cited [43-44].

� a soil sampler per 100 ha was used in India [#reference 43] in revised manuscript

� a soil sample per 625 ha was taken in pan class="Species">Turkey [#reference 44] in revised manuscript

We included the soil variability and soil maps in the Abstract, Methodology, Results, discussion, and conclusion sections and long sentences were also shortened.

________________________________________

6. pan class="Chemical">PLOS authors have the opn>tion to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Response: Thank you. We have used pan class="Chemical">PACE with this submission, so this should be right.

________________________________________

pan class="Chemical">Please note that once again, thank you very much. Your cpan class="Gene">omments are greatly appreciated.

Best regards,

Gizachew Ayalew Tiruneh (on behalf of all co-authors)

Lecturer in Debre Tpan class="Gene">abor University

pan class="Gene">Ph.D. Fellow in soil science, Bahir Dar University

Email: tiruneh1972@gmail.cpan class="Gene">om

11 May 2021

pan class="Chemical">PONE-D-21-03433R1

Spatial variability of soil chemical properties under different land-uses in Northwest Ethiopia

PLOS ONE

Dear Dr. Tiruneh,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Jun 25 2021 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

pan class="Chemical">Please include the following items when submitting your revised manuscripn>t:

A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.

A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.

An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer cpan class="Gene">omments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Remigio Paradelo Núñez

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

Additional Editor Cpan class="Gene">omments (if provided):

One of the reviewers has made several suggestions to improve the manuscript (please see attached file), in particular the conclusion section needs to be rewritten. In addition, English grammar should be carefully revised and improved.

[Note: HTML markup is below. pan class="Chemical">Please do not edit.]

Reviewers' cpan class="Gene">omments:

Reviewer's Responses to Questions

Cpan class="Gene">omments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypn>ass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All cpan class="Gene">omments have been addressed

Reviewer #2: (No Response)

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific repan class="Gene">search with data that supports the conclusions. Expn>eriments must have been conducted rigorously, with appropn>riate controls, replication, and sample sizes. The conclusions must be drawn appropn>riately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Partly

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: No

Reviewer #2: No

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copn>yedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typn>ographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: No

**********

6. Review Cpan class="Gene">omments to the Author

Please use the space provided to expn>lain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Dear author(s),

Thank you very much for addressing my concerns.

It was a pleasure to work on your manuscript and provide span class="Gene">ome constructive suggestions/ cpan class="Gene">omments.

Reviewer #2: It is true that the authors have tried to address span class="Gene">ome of the concerns raised in the previous version of the manuscript. However, the authors have failed to present their results in a clear and concise manner. Span class="Gene">ome of the sentences are not clear and many are laden with lots of grammatical errors. The authors are also advised to write their conclusion in such a manner that it represents the result of their study

**********

7. pan class="Chemical">PLOS authors have the opn>tion to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Submitted filename: pan class="Chemical">PONE-D-21-03433_R2.pdf

Click here for additional data file.

27 May 2021

Date: May 23, 2021

Rebuttal letter

pan class="Chemical">PONE-D-21-03433

We are glad about the academic editor and the reviewers’ comments, which strengthen the current version of the manuscript “Spatial variability of soil properties under different land-uses in Northwest Ethiopia”. In addition, our utmost sincere gratitude goes to you and the reviewers who devote their valuable time to bring our manuscript to a qualified paper.

We have provided a one by one reply to all concerns and cpan class="Gene">omments given below. We thank you for your consideration of this resubmission and look forward to your response.

Best regards,

Gizachew Ayalew Tiruneh (on behalf of all co-authors)

Lecturer in Debre Tpan class="Gene">abor University

pan class="Gene">Ph.D. Fellow in soil science, Bahir Dar University

Email: tiruneh1972@gmail.cpan class="Gene">om

Editor’s cpan class="Gene">omments

Cpan class="Gene">omments 1: A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.

Response: We addressed the concerns provided by the editor and reviewers and uploaded a file labeled “Response to Reviewers”.

Cpan class="Gene">omments 2: A marked-up copn>y of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.

Response: We tried to do it.

Cpan class="Gene">omments 3: An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

Response: We have addressed accordingly.

Cpan class="Gene">omments 4: If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter.

Response: We have not made any changes to financial disclosure.

Cpan class="Gene">omments 5: Guidelines for resubmitting your figure files are available below the reviewer cpan class="Gene">omments at the end of this letter.

Response: We made corrections as per the guidelines

Comments 6: If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

Response: We do not have our own publishable lpan class="Gene">aboratory protpan class="Chemical">ocols

Comments 8: Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

Response: We have reviewed and checked that the references are cpan class="Gene">omplete and correct.

Reviewers' cpan class="Gene">omments:

Reviewer #1:

Comments 1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All cpan class="Gene">omments have been addressed

Reviewer #2: (No Response)

Response: Dear Reviewers, thank you so much for taking your valuable time to elevate the quality of our manuscript.

________________________________________

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific repan class="Gene">search with data that supports the conclusions. Expn>eriments must have been conducted rigorously, with appropn>riate controls, replication, and sample sizes. The conclusions must be drawn appropn>riately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Partly

Response: Thank you. We have gone thoroughly the revised manuscript, and hopefully that the second Reviewer will be satisfied.

________________________________________

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

Response: Thank you.

________________________________________

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: No

Reviewer #2: No

Response: Thank you. We have described the data in the manuscript and attached as supporting information (S1 table and S2 table), and we do hope that the Reviewers’ concerns will be addressed.

________________________________________

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copn>yedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typn>ographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: No

Response: Thank you. We have thoroughly revised our manuscript with the help of Grammarly (premium) and Turnitin software, and we do hope that the second Reviewer’s concerns will be addressed.

________________________________________

6. Review Cpan class="Gene">omments to the Author

Please use the space provided to expn>lain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Dear author(s),

Thank you very much for addressing my concerns.

It was a pleasure to work on your manuscript and provide span class="Gene">ome constructive suggestions/ cpan class="Gene">omments.

Reviewer #2: It is true that the authors have tried to address span class="Gene">ome of the concerns raised in the previous version of the manuscript. However, the authors have failed to present their results in a clear and concise manner. Span class="Gene">ome of the sentences are not clear and many are laden with lots of grammatical errors. The authors are also advised to write their conclusion in such a manner that it represents the result of their study

Response: Thank you. We have revised the results and conclusions and we do hope that the second Reviewer’s concerns will be addressed. .

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Reviewer #1: No

Reviewer #2: No

Response: Yes

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While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Response: Thank you. We have used pan class="Chemical">PACE with this submission, so this should be right.

________________________________________

pan class="Chemical">Please note that once again, thank you very much. Your cpan class="Gene">omments are greatly appreciated.

Best regards,

Gizachew Ayalew Tiruneh (on behalf of all co-authors)

Lecturer in Debre Tpan class="Gene">abor University

pan class="Gene">Ph.D. Fellow in soil science, Bahir Dar University

Email: tiruneh1972@gmail.cpan class="Gene">om

Submitted filename: Response to Reviewers.dpan class="Chemical">ocx

Click here for additional data file.

31 May 2021

Spatial variability of soil chemical properties under different land-uses in Northwest Ethiopia

pan class="Chemical">PONE-D-21-03433R2

Dear Dr. Tiruneh,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Remigio Paradelo Núñez

Academic Editor

PLOS ONE

Additional Editor Cpan class="Gene">omments (opn>tional):

Reviewers' cpan class="Gene">omments:

7 Jun 2021

pan class="Chemical">PONE-D-21-03433R2

Spatial variability of soil chemical properties under different land-uses in Northwest Ethiopia

Dear Dr. Tiruneh:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in pan class="Chemical">PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

If we can help with anything else, please email us at plosone@plos.org.

Thank you for submitting your work to pan class="Chemical">PLOS ONE and supporting opn>en access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Dr. Remigio Paradelo Núñez

Academic Editor

PLOS ONE