Effect Of Different NP Ratios On Soil Nutrients, Corn Nutrient Absorption Characteristics, Yields And Quality

Spring corn is one of the crops that cultivated widely in Gansu province recently.But low yield due to extentive management.In order to understand the nutrition regulation of spring corn, the characteristics of fertilizer requirement and then make out appropriate measures,the field experiment were conducted to study the content,uptake and distribution of nitrogen, phosphorus and potassium and the effects of available nitrogen, phosphorus, potassium in soil, yields,protein content, fat content,starch content and lysine content in spring corn. The results showed as follow:1. Effects of corn growth rate in different N and P is mainly in a certain range ,N and P can promote corn growth speed up, and excessive decline. Leaf area index under the influence of nitrogen, phosphate fertilizer is improved,but phosphorus is less than nitrogen. The net photosynthetic rate changes "M" type in corn life, with nitrogen levels from low (N: 300 kg hm-2) to medium (N: 600kg hm-2), the increase in net photosynthetic rate and the nitrogen from mediun to high (N: 750kg hm-2), appeared to net photosynthetic rate is decline. Influence of dry matter accumulation in different fertilizer levels for the performance of slow growth early, from jointing stage to tasseling, vegetative growth and reproductive growth in hand , so the dry matter accumulation quantity increases,and the tasseling stage is maximum. To mature stage is reduce. In the same period, the amount of nitrogen and phosphate increased can increase dry matter accumulation quantity significantly ,but more than optimal proportion, it will cause drop. In all treatments, the growth rate, leaf area index, net photosynthetic rate and dry matter accumulation is maximum of N3P2. In the R/S, increased N and P can promote R/S, but the nitrogen is better than phosphorus and the biggest processing for N2P3.2. The NPK absorption of spring corn in seedling and jointing stage is slow, mainly concentrated in the trumpet and tasseling stage. For different fertilizer processing, the absorption of nutrient. in corn leaf, sheath, stem and root are as nitrogen increased as added. The treatment of the largest quantity nitrogen for N3P2. From parts of distribution, in the vegetative growth stage, the N P K mainly concentrated in the foliar, with 38.4%-48.9%, 37.4%-41.1% and 30.2%-45.7%;the stem with 23.1%-31.8%,27.9%-30.9% and 26.4%- 35.7%; root with 15.4%-18.1%,20.7%-30.7% and 18.2%-20.8%; the sheath with 9.9%- 13.7%,4.2%-12.0% and 10.9%-16.4%. Along with the growth of corn, the nutrients are transferred into grain, bract and rod shaft. In the mature stage, Most of the N P K are tran- -sferred into the grain, with 64.0%,52.3% and 60.3%, respectively.In high phosphorus, nutrient harvest index is increased.with nitrogen fertilizer added. The nutrient harvest index is added with 0.2-0.6,1.6-3.8,0.9-1.2 percentage points. With the increasd of phosphorus, nutrient harvest index does not change significantly.3. The effect of fertilizer for corn yield is bigger. But different fertilizer has no obvious influence in corn spike length, coarse and row number per ear. As fertilizer added, especially nitrogen, the corn spike length, coarse and row number per ear are increased, and bald pointed length is decreased. For the final yield, increasing nitrogen and phosphorus can raise yield, but the result of nitrogen is better than phosphorus. The order of yield is N3P2>N2P1>N2P0>N2P3>N2P2>N4P3>N4P2>N1P2>N1P1>CK, and the largest yield is 17545.8 kg hm-2. Effect of different N and P levels in corn quality is along with the increase of nitrogen ,the protein, fat, starch and lysine are increased. But nitrgon is fixed and raise phosphorus can increase the content of fat and lysine. The maximum range is 5.8%-116.7%, and for the content of protein and starch is little.4. Different fertilizer on the performance of soil available nutrient for the "M" type. In the jointing stage and tasseling has two peak. For different treatment, increasing N and P can promote soil available nutrient, but only in the high level of N and P, soil available nutrient will increase significantly. In this experiment, the soil available nutrient ratio for the biggest 600 kg hm-2(N) and 120 kg hm-2(P).5. Correlation showed that : in corn seedling, no correlation between plant nutrient uptake, while in jointing stage, the trumpet, tasseling and maturity, between all the absorption of nutrient are high significantly positive correlation. In corn growth, between plant nutrient absorption and soil nutrients have high significant correlation, Only in seedling plant to absorption of nitrogen has no correlation with soil available potassium and in maturity, plant to absorption of nitrogen and phosphorus have no correlation with soil available nutrients. plant to absorption of N P K and corn yields have significantly positive correlation, especially, the correlation with nitrogen is high have significantly. Corn protein content and N P K in plant have no correlation, others has significantly correlation. Corn fat content and N P K in plant all have significantly correlation. The starch content has significantly correlation with the absorption of N in plant, but not correlation with the absorption of Pand K. Between the absorption of N P K in plant and corn lysine content has high significantly positive correlation.