Water Dynamics Combined with a Supply of NPK Solutes and Urea in a 3-Layer Soil Profile under Drip Irrigation

摘要

The intensive and inappropriate use of water, fertilizers and phytosanitary products is sources of water and soil pollution. It is thus necessary to improve the management of irrigation water in order to optimize its use and productivity, especially in regions where water resources are becoming increasingly scarce. The water flow and non-reactive solutes’ transport simulation under drip irrigation were carried out in a 3-layered soil profile distributed from top to bottom i.e ., sandy, sandy-silty, silty-sandy-clay. The aim of this study was thus, to provide a good practice of water management associated with solutes’ application, in order to retain as much solute as possible in the root zone, which will increase the residence time of the solutes. Three treatments of water flux corresponding to 100% ET _( c ), 75% ET _( c ), 50% ET _( c ), combined with 100 mmol /L/ m~(2) of NPK and 246 mmol/L/m~(2) of urea applicable in two doses, were carried out over a period of 110 days corresponding to the duration of the cropping cycle for the intermediate variety of maize. The 100% ET _( c ) and 75% ET _( c ) treatments cause more loss of water and solutes, because of the sandy texture of the soil. However, a 50% ET _( c ) water flux would reduce more water loss through drainage, and solutes’ loss due to leaching beyond the root zone, which would increase the residence time of solutes in the soil profile. Application tests of the NPK solute on different days before the 15~(th) day after sowing were also carried out according to the technical itinerary for maize production in Burkina Faso, in order to find a favorable day for application of the solute. For the different dates of solute’s application, there was more loss of the solute as we approach the 15~(th) day after sowing. To limit this loss and increase the residence time of the NPK solute, one could apply the solute without first supplying water, the day before and the day after the date of solute’ injection. Or, one could amend the soil with organic matter to improve its retention capacity of water, and the solutes’ residence time in the soil.