Study On Water-fertilizer Effect And Irrigation Models Of Rice In Sanjiang Plian

Sanjiang Plain is famous commodity grain base in China, rice is an important food crop。Total water resources are relatively abundant in the region, but the regional distribution is uneven. In the regions using surface water,serious waste of widespread exists;In the regions using underground water, rice has a lower yield and excessive groundwater are exploited. In recent years, with area of rice using undergroundwater increasing, the balance of undergroundwater is seriously distroyed. In the long process of agricultural development, a series of ecological and environmental problems happened, such as declining area of wetland, agricultural non-point source pollution and serious water pollution.How to solve the above problems is the purpose of this article.Water and fertilizer, as two important factors of crop product, to some extent, determine yields. Under water-saving condition, crop growth environment changes and the interaction of water and fertilizer becomes more complex, which makes it more difficultly to study the relations between water and fertilizer. former water-fertilizer product functions, analyzing their advantages and disadvantages, the rice water-fertilizer(N,P,K) product function models was established. For the crop production, especially under water-saving condition, it has important significance.Both of field test and laboratory analysis were adopted. In Chapterâ…¡, it analyzes the effect of different water-saving irrigation models on rice growth status and studies the water consumption regularities of different water-saving irrigation models. In Chapterâ…¢, it analyzes and compares the effects on rice growth status and environment between water-saving irrigation model and coupling water-fertilizer techniques. And then, it systematically studies factors of crop growth and development, which refer to water stress,nitrogen deficit and portion of N,P,K under different irrigation models. For different coupling water-fertilizer conditions, it analyzes characters of NH₄⁺-N and NO₃^--N in surface water and their influence on index of soil nutrient. In addition, it takes fuzzy comprehensive evaluation method to analyze soil nutrient. In Chapterâ…£, it develops water product function of phrase, adds an fertilizer effect function and proposes Jensen Model referring to water and nitrogen for the rice production in this region; it first develops modified Morgan Model referring to water and N,P,K. The modified Morgan Model referring to referring to water and N,P,K is innovation.It has conclusions as following: 1) Water-saving irrigation model not only have significant effect of water-saving and profoundly influence on the growth and development of rice, but also affect ecology environment and conduce to high yield of rice and improvement of ecology environment. Related research results show that rice adopting wet irrigation has most tillers in the early growth stage and is first to have tillering peak , rice adopting control irrigation and flood irrigation don't have so many tillers and in the end of tillering stage, rice adopting flood irrigation has more tillers than one of control irrigation. Different irrigation models have different effects on height, LAI, dry matter accumulation above ground. For water consumption , control irrigation has the least water consumption, wet irrigation has 43.5% water consumption more than control irrigation, the flood irrigation has the most water consumption. For rice yield, control irrigation has the less yield than wet irrigation and flood irrigation, wet irrigation has 23.1% more than control irrigation and flood irrigation has 9.02%. For 853 Farm in Baoqing, the underground water balance was calculated. The results showed the underground water is in a state of negative equilibrium. It proposes, for different irrigation models , some appropriate approaches to develop underground water and use ground water, which can save water resource to some extent and promote underground water to a equilibrium state.2) It analyzes the effect of water stress and nitrogen deficit on growth status, yield and WUE of rice. The conclusions are as following :In the same irrigation model, high level of nitrogen can promote rice to tillering; In the same nitrogen level, Treatment W4 has the highest LAI. Treatment of no nitrogen has the lowest WUE and Treatment of normal level has the middle WUE. It analyzes the effects of water and nitrogen on yield and component factors. The conclusions are as following: Nitrogen has a positive effect on yield and its component factors and the higher nitrogen level, the greater effect; Water control and interaction of water stress and nitrogen has a negative effect on yield and its component factors; Interaction of water and nitrogen has greatest effect on panicles per square meter, which is part of rice yield component factors. Nitrogen has a greater effect on yield than water does. In field tests, Treatment of nitrogen level of 330kg/hm² and W₃ has the highest yield and it is the best combination to save water and get high yield.3)Known form analyzing soil nutrient, nitrogen accumulation rate in soil increased 44.5% than before transplanting when nitrogen rate is 330kg/hm². The higher is nitrogen rate, more serious is nitrogen residue corresponding, with the increasing of nitrogen rate, soil available nitrogen content also increases, but the amplitude is smaller.Compare the soil organic matter before transplanting and after harvest, with the enhance of nitrogen rate, the soil organic matter presents faint increasing trend, beside individual no-nitrogen and middle–nitrogen treatments, it shows the effect nitrogen rate on soil organic matter is small, and soil organic matter more stable. Known form nitrogen concentration test, the bigger is nitrogen rate, the higher is NH₄⁺-N and NO₃^--N concentration. The highest value of NH₄⁺-N concentration in paddy surface water appeared in the third day after turning green fertilizer. The highest value of NH₄⁺-N concentration appeared in the second day after panicle fertilizer, the time of the highest value of NO₃^--N concentration appeared latter than NH₄⁺-N one day. Using fuzzy comprehensive evaluate method to assess soil fertilizer quality, draw a conclusion that soil fertilizer grade is related closely with nitrogen rate, the soil grade of no-nitrogen plot is lower, and it is higher in high-nitrogen plot.4) Under the condition of N,P,K combined application and topdressing, the change of NH₄⁺-N and NO₃^--N concentration in paddy surface water, there is its characters except the time of the peak appear is consist with the water stress and nitrogen deficit condition. The concentration of N₃P₂K₂ treatment, especially the concentration under wetting irrigation is higher than under common irrigation, the difference between the concentration of N₁P₃K₂ and N₂P₃K₁ is not significant.The phosphate application rate has direct effect on the NH₄⁺-N concentration in paddy surface water, the effect potassium on the NH₄⁺-N concentration in paddy surface water needs to research. The concentration reachs to peak value faster after panicle fertilizer than that of after green fertilizer, and the concentration is bigger, the time of fertilizer is latter, therefore the concentration is higher in the treatment which fertilizer according to F₂ proportion than the F₁ proportion. The range of NO₃^--N concentration value is similar after green fertilizer and spike fertilizer, although it encounters rainfall after tillering fertilizer, the NO₃^--N concentration is higher all the same, and the differences in each treatment are not significant. Soil fertility quality was evaluated with the fuzzy comprehensive evaluation method, and the grade of each plot was made sure, the soil fertility quality of N₁P₃K₂ treatment plot belongs to middle, N₃P₂K₂ and N₂P₃K₁ belongs to high grade, the soil fertility quality of plot fertilizerd as F₂ proportion is higher than as F₁.5) Rice water and fertility production function reflects the quantitative effect field water and fertilizer and their interaction on paddy yield. The water and nitrogen production fuction growth stage model,Jensen model, and water and nitrogen dynamic production function ,Correction Morgan model were build, which have certain predict fuction and higher fitting degree, in real application can accord to practical condition and requirement chooses model. Based on rice water and nitrogen production function model, the paper constructed rice water and nitrogen, phosphorus and potassium production function models, they are water and fertility growth grade Jensen model and water and fertility dynamic production function correction Morgan model. Jensen model can reflect the effect water stress and fertility deficit in growth grades on crops, can predict production according to water amount and fertilizer condition, the parameters of models are reliable, the models have reference function in product praction. Correction Morgan model introduces fertility effect function on the basis of water production function dynamic model, it can simulate the response the accumulate procession of dry matter on water and fertilizer, reflect the interaction between crop growth and water and fertilizer, predict the effect on yield according to the rate of nitrogen, phosphorus and potassium, more detailed simulate the growth process in different water and fertilizer, the correlation coefficient is higher, provide evidence for scientific saving-water and rational fertilization.