Fate of Nitrate In Soil Cultivated With Maize (Zea mays L.) Under Different Patterns of Irrigation Regime and Localized Compaction

The objective of this study was to evaluate the localized compaction (LC) and irrigation regime application management on maize (Zea mays L.) growth grown in calcareous soil and nitrate leaching from a maize field and also to evaluate LEACHM model for predicting water, and nitrate spatial and temporally in the soil. Field experiment was carried out using calcareous sandy loam soil in ELBoston region, West Nile Delta, Egypt, under furrow irrigation system. Two water irrigation regimes were used: Field capacity (I-1) and Saturation (I-2) as upper limits for soil water contents. The lower limit for irrigation for both regimes is 50% of soil available water. Ammonium nitrate fertilizer was banded with four treatments of localized compaction: control without compaction (LC-1), compaction under a fertilizer band (LC-2), compaction above a fertilizer band (LC-3) and a combination of the previous two positions (LC-4). The four compaction techniques did not affect significantly the soil nitrate concentrations under F.C. irrigation treatment (I1). There were significant differences between the two irrigation regimes (I-2 and I-1) in grain yield, ear weight, ear tall, ear diameter, leaf surface area, plant height, stem diameter, leaf fresh and dry weight, plant biomass production, total dry matter and nitrate leaching losses. These differences may be due excessive NO-3 leaching in I2 irrigation treatment. Leaching losses of NO-3 of I-1 irrigation treatment decreased by 75.68% with comparison to I-2 irrigation treatment. The average leaching losses for localized compaction treatments under I-1 irrigation were 36.43, 38.10, 31.22 and 31.86 kg ha-1, respectively, and the corresponding losses for I-2 irrigation were 177.76, 179.85, 104.31 and 103.93 kg ha-1 for LC-1, LC-2, LC-3, and LC-4, respectively. The LEACHM model well predicted the concentrations of NO-3 in soil profile and leachate as compared with the observed values. The ability of the model for NO-3 prediction was evaluated using different statically scales which proved that LEACHM model is a useful tool for optimizing and managing the application of irrigation water and N fertilizer in maize field under the used experimental conditions.