Nitrogen dynamics in soil and maize yield as affected by drip fertigation splits and rates in semi-humid region

摘要

In semi-humid regions of Northeast China, drip fertigation is increasingly used for maize production to cope with the frequent occurrence of drought and decreasing water allocation to agricultural irrigation. For conventional maize cultivation in thisregion, the total dose of nitrogen fertilizer is usually broadcasted at the early season to avoid the difficult accessibility during the late season. Drip fertigation made the in-season fertilization possible. Field experiments were conducted in Heilongjiang Province to investigate the influences of fertigation splits and nitrogen applied on crop growth and nitrogen dynamics in soil during the growing season of maize in 2011 and 2012. In the experiments, a single fertigation at the jointing stage and three fertigation splits at the jointing, heading and filling stages were used. For each treatment of fertigation splits, four nitrogen levels of 50, 100, 150 and 200 kg N ha were tested using a randomized complete block design (RCBD) with three replications. The results indicated that, for a given amount of nitrogen applied, the three fertigation splits increased the nitrate in the root zone during the growing season and decreased the residual nitrate at the deep layer, reducing the potential risk of nitrate leaching out of the root zone. The increasing fertigation splits and nitrogen applied increased the nitrogen uptake of maize at the filling stage. Furthermore, the three fertigation splits in season produced a significantly higher yield than the single fertigation at the early season. A greater amount of nitrogen applied produced a higher maize yield for either the single fertigation or the three fertigation splits in both years, but the difference between the nitrogen rate of 150 kg ha~(-1) and 200 kg ha~(-1) was not statistically significant. We recommended a management practice of 150-200 kg ha~(-1) of nitrogenapplied at three fertigation splits to obtain high production while reducing the risk of nitrogen leaching.