Micro Irrigation – A Technique to Reduce Nitrate Leaching

Producing an adequate quantity of healthy food without polluting the environment is a formidable challenge for future agriculture in the world. Leaching of nitrate from agricultural land and from other sources to groundwater is a global phenomenon. A properly designed micro fertigation systems delivers water and nutrients, at a rate, duration and frequency, so as to maximize crop water and nutrient uptake, while minimizing leaching of nutrients and chemicals from the root zone of agricultural fields. Nitrate losses are likely to be more when all the nitrogen is applied in one application compared to when nitrogen is applied in split applications which is only possible through high frequency micro irrigation. Nitrate losses from fertilizer use can be reduced by matching fertilizer application with nitrogen needs of a crop. Nitrogen fertilizers applied on a sandy soil are more vulnerable to leaching to groundwater than nitrogen used on a clay soil. Fertilizer was applied through daily, alternate day and weekly fertigation frequency shows that NO₃-N in lower soil profiles (30–60 cm soil depth), was marginally affected. The total available NO₃-N in soil in all fertigation frequency is almost same. The distribution of NO₃-N in soil profile is very greatly influenced by fertigation frequency in sandy-loam soil. The average NO₃-N content of lower soil profile (45–60 cm soil depth) remained relatively unchanged. The largest losses of NO₃-N occurred from 30–45 cm soil depth in monthly fertigation frequency. It was concluded that losses can be minimized by adopting the micro irrigation system with more frequent application of nitrogenous fertilizers.