Effects of residual plastic-film mulch on field corn growth and productivity.

Plastic-film mulching has played an important role to promote agricultural production in arid areas; however, due to its inefficient recycling capacity, large amounts of residues have been accumulated in soils, causing negative impacts on crop growth and on the environment. To investigate these effects on water use efficiency, a two-years field experiment was carried out, applying different levels of plastic-film residues, from 0 to 600 kg ha-1. Results show that these residues have a negative impact on root and shoot growth at several growth stages of corn crop, particularly if above 300 kg ha-1. Root length and weight density decrease with the amount of residues throughout the majority of crop season. Plastic-film residues of about 600 kg ha-1 are responsible for the decrease of the biomass root to shoot ratio during the tasseling stage. Moreover, during physiological maturity, root and shoot revealed the highest sensitivity, and the least negative effects on the root system. Results also show that crop water consumption has a slight decrease with the plastic-film residues, though there was also a significant decrease of the yield and the water use efficiency reduction. This information allows to state that it is determinant to learn how to deal with the problem, adjusting the irrigation and crop management to avoid yield impacts. It would also be important to find an efficient procedure to mechanically collect the residues in the soil, and to apply new biodegradable film mulching.