Study On High Efficient Utilization Of Spring Wheat-Silage Maize Cropping Nitrogen

In traditional farming system the heat resource of North Region of Xinjiang is "more than one cropping, not enough for double cropping". In the adjustment of agricultural structure, animal husbandry was planned to be vigorously developed. But it is necessary to study on how to combine drip irrigation, no-tillage and reasonable fertilization technologies to ensure that agriculture could provide enough food for people and also meet the forage demand of livestock. So "drip irrigation of wheat and silage corn multiple cropping pattern with no-tillage" is particularly urgent. Meanwhile how to use the reasonable and efficient nitrogen fertilizer application in the drip irrigation system of wheat- silage maize is one of the key technologies for the successful development of the model. Therefore, the research with different nitrogen amount on wheat and silage maize were respectively,carried out to study those two crops’ yield, nitrogen distribution in the soil and plant, circulation and utilization efficiency, so as to improve the nitrogen fertilizer anniversary utilization efficiency in the planting pattern and reduce nitrogen loss, improve crops’ yield and income. It would support the local agricultural structure adjustment and benefit farmer also. The following results are obtained through the study:(1) Anniversary space-time distribution characteristics of soil ammoniacal nitrogen and nitrate nitrogen under different nitrogen treatments in double cropping system: in terms of spatial distribution, for the previous crop, spring wheat, the soil ammonium nitrogen and nitrate nitrogen content were decreased with the deepening of soil depth in the same growth period; with the growth period, in the same soil layer, the ammonia nitrogen content showed the trend of increasing firstly, then decreasing and then increasing again, and at booting stage of wheat reaching the maximum; however, soil nitrate nitrogen content revealed a trend of steady rise during the growth stage processes. In the subsequent crop silage maize seedling stage soil ammonia nitrogen content in 0-20 cm depth increased with the increase of nitrogen mount. In Nw1 nitrogen treatment except that soil ammonia nitrogen content of the silage maize showed a decreasing trend with the soil depth, the other treatments were on the contrary.So soil ammonia nitrogen spatial distribution rule was not very clear. After seedling stage, the soil ammonium nitrogen content significantly decreased, but it got a small amount of rebound at bell stage and then continued to decline. On the other hand, soil nitrate nitrogen content was always much higher than ammoniacal nitrogen content except(2) Partitioning characteristics of nitrogen in subsequent crop, silage maize, at different growth stages: at jointing stage of spring wheat leaf was the most important part where nitrogen was distribute; at bell stage nitrogen distribution proportion to stem was improved,till flowering stage nitrogen distribution to stem had reached the highest at the same time leaf got lower nitrogen distribution proportion; during postulation period the nitrogen distributionratio to spike was generally more than 50%, meanwhile stem’s and leaf’s nitrogen distribution proportion were basically the same, accounted for about 25%. Overall, from the jointing stage to filling stage total nitrogen accumulation was in steady upward trend, and from grain filling stage to maturity stage the nitrogen accumulation showed differences, in which the whole plant nitrogen accumulation increased from 182.11kg/hm2 to 247.88kg/hm2, increasing by36.12% in NW2NC2 processing.(3) The wheat yield increased with the increase of the amount of nitrogen fertilizer in the spring wheat, and the growing rate of wheat yield increased with the increase of nitrogen application amount, however, the partial productivity and agronomic efficiency of nitrogen fertilizer decreased in different degrees. As the silage maize biomass as be concerned, it increased with nitrogen application rate’s increase during different nitrogen treatments, but in the same previous crop nitrogen condition the partial factor productivity applied nitrogen,decreased with the nitrogen application amount increase of subsequent crop, which means less nitrogen fertilizer can increase the nitrogen partial productivity under the same nitrogen treatment of wheat. Nitrogen agronomy efficiency in NW0、NW1 treatments were increased with the increase of silage maize in the same previous crop nitrogen treatment, but decreased in NW2、NW3 treatments, therefore low nitrogen treatment in wheat planting succeeding high nitrogen rate in silage maize or high nitrogen treatment in wheat planting succeeding low nitrogen rate in silage maize would be beneficial to improve nitrogen agronomy efficiency.(4) By means the nitrogen apparent loss in the study we found that, in this experiment NW1NC0 treatment at the end of cropping cycle the total nitrogen content residue in soil was lowest, significantly lower than other treatments. And in NW0NC1, NW1NC1, NW2NC1 processing the residual nitrogen amounts in soil were slightly higher than NW1NC0 treatment, but they were also low. So in double cropping system with the constant total nitrogen rate if nitrogen fertilizer was reasonably collocated, it would be not only helpful for the plant’s vegetative growth and reproductive growth at the important period to ensure the plant get good growth development, but also ensure the soil nitrogen not excessive to leach but enough to meet the soil nitrogen pool complement demand so as to improve soil fertility.(5) In this study, the NW2NC1 treatment obtained the largest economic returns, and the crop yield, total nitrogen accumulation of two crop plants, nitrogen use efficiency, nitrogen partial productivity and nitrogen agronomic efficiency are also better. Therefore, from the view of economic benefit and efficient use of nitrogen fertilizer, NW2NC1 is the best nitrogen application in this study.