| China is poor in water resource, water is wasted and water utilization efficiency is low; fertilizer especially nitrogenous fertilizer is most important to increasing grain yield, its dose is large and low efficiency of nitrogen utilization has been a important problem of farming production. For improving water and nitrogen use efficiency, many home and abroad scholars make much research on the mechanism of water promoting fertilizer, fertilizer adjusting water and water-fertilizer coupling effects and models. But the research is more in dry region, vacant in humid region.In Chongqing, 54.56% dry land and 15.34% dry yield constitute big proportion dry farming of moist region. Because of hilly land, dry slope land is many, low fertility. The spring maize which has big planting area, much requirement of water and fertilizer, is often threatened by drought in spring and summer. So the contradiction of water and fertilizer is more apparently at the top of dry slope land.Considering above-mentioned situation, with three typical soils of southwest humid region, the study was carried out on the effect of different soil water to nitrogen mineralizer, on the basis of which, pot experiment was conducted with neutral purple soil of the top slope land and the spring maize as the materials, adopted the design of the total project with three nitrogen levels and four water types, under surperphosphate(0.2 g P205 percent kg dry soil) and potassium chloride(0.2 g K20 percent kg dry soil). The results show:The effect of water to soil nitrogen mineralizer was serious. From soil water stress to soil water comparative content 60%?0% which was the best, nitrogen mineralizer amounts increased with water rising by linear dependence, decreased with water continuous rising. With nitrogen fertilizer applied, soil nitrogen mineralizer capacity and intensity all improved, but the law of water to soil nitrogen mineralizer was not changed compare to no N fertilizer. No matter that nitrogen fertilizer was applied or not, the mineralizer difference of acid purple soil, neutral purple soil and calcareous purple soil was caused by soil texture.In the range of soil water absolute contentl0%?5%, the maize height increased with water rising, among which, restriction of water stress was more than promoting of plenty water. Water stress 10% delayed the maize growth period 10 days.To the low fertility soil, only from water absolute content 10% to 20%, the maize yield increased with water rising, but not notability. Water seriously influenced nitrogen fertilizer increasing yield. At 10% soil water absolute content, nitrogen fertilizer hasn3the yield increment effect; from 15% to 25%, nitrogen fertilizer obviously increased maize yield by >4 times. There was a linear correlation between the maize yield and water. It was water rising that improved fertilizer nitrogen uptake and nitrogen use efficiency(NUE), the maize yield increased, but the maize nitrogen content detracted. Nitrogen ratio of seeds to stalk and leaves could be increased from drought (10%) to normal water( 20%), decreased at plenty water(25%).After the maize was harvested, the remained available nitrogen of soil was not apparently influenced by water at no nitrogen fertilizer, reduced with water up at applying nitrogen fertilizer.N fertilization could promote the root growth, increase the root vigor and the transpiration intensity, strengthen the ability that the maize absorbed and transit water and nutrient, amplify function leave dimension and chlorophyll content which strengthened photosynthesis, especially in drought condition it improved the water capacity of the maize leaves and infiltration adjusting impact, which made the maize strengthen its drought resistant, at last the maize yield was increased.Except water stress 10%, N fertilization could heighten the maize water consumption, what is more , water use efticiency(WUE) which was the basis of the maize yield increment. The treatments with O.5g N per kg dry soil increased WUE not more than... |
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