Effects Of Straw Returning On Maize Nutrient Uptake And Soil Nutrient Change Based On ¹⁵N Tracer Technique

In order to avoid resource waste and environmental pollution caused by unreasonable utilization of straw resources in Northeast China,the straw returning test was carried out on calcareous chernozem soil in semi-arid area of Heilongjiang Province.The ¹⁵N tracer technology was used to select"Xianyu 335"as the test variety.Five treatments were set and they were:CK treatment:no nitrogen fertilizer was applied;A treatment:basal fertilizer N50%(¹⁵N-labeled urea)+topdressing N 50%(¹⁵N-labeled urea)-（A1）;Basal fertilizer N accounted for 50%（common urea）+topdressing N accounted for 50%(¹⁵N labeled urea)-（A2）;C treatment（straw returning）:basal fertilizer N accounted for 50%(¹⁵N-labeled urea)+topdressing N accounted for 50%(¹⁵N-labeled urea)-（C1）;Basal fertilizer N 50%（common urea）+topdressing N 50%^{（15）N labeled urea}-（C2）.By measuring quality of corn Leaf SPAD yields agronomic traits at different development stages Dry matter accumulation Each organ allocation of nutrients uptake of soil nutrient content and soil enzyme activity and study of nitrogen absorption efficiency,straw returned to heilongjiang western semi-arid areas to provide the theoretical basis and optimized nitrogen management to provide theoretical support the results of the study were as follows:1.Under the straw returning condition,compared with those without straw returning,the crude lipid and starch contents of corn grains were increased by 9.14%and 14.69%,respectively.The SPAD value of maize leaves had no significant difference except at silking stage.The plant height of maize increased by 1.87%～10.62%from trumpet stage to grain filling stage,but had no obvious effect on the stem diameter of maize.From jointing stage to silking stage,dry matter accumulation increased by 4.38%～39.95%,and decreased by4.66%～8.49%from grain filling stage to maturity stage.The yield was significantly reduced by 5.98%.2.After the straw was returned to the field,the nitrogen accumulation at jointing stage was increased by 27.70%,and the nitrogen accumulation at trumpet stage and mature stage was decreased by 4.05%and 5.37%,while the nitrogen accumulation at other growth stages was not significantly affected.Phosphate accumulation increased by 4.46%～43.86%from jointing stage to silking stage,and decreased by 3.73%～11.55%from grain filling stage to maturity stage.From jointing stage to silking stage,potassium accumulation increased by7.80%～64.05%,and decreased by 4.02%～10.50%from grain filling stage to maturity stage.3.Under the condition of local conventional fertilization,the nitrogen use efficiency calculated by tracer method was 25.10%,among which,the nitrogen use efficiency of base fertilizer was 7.94%,and that of topdressing fertilizer was 42.21%.The nitrogen use efficiency was 66.03%and the base fertilizer use efficiency was 20.86%by subtraction method.Under the condition of straw quantitative return,the nitrogen use efficiency calculated by tracer method was 28.41%,of which,the nitrogen use efficiency of base fertilizer was 10.04%,and that of topdressing fertilizer was 46.73%.The nitrogen use efficiency and base fertilizer use efficiency were 55.76%and 38.01%by subtraction method.4.Under the condition of quantitative straw returning,the urease activity in 0-20cm soil layer increased by 5.00%and 13.64%at jointing and maturity stages,respectively,compared with that without straw returning.There was no obvious effect on alkaline phosphatase activity.The activity of sucrase increased by 22.23%and 7.66%at jointing and maturity stages,respectively.The activity of catalase was increased by 2.15%and 2.15%at the bell-honking stage and mature stage,respectively.In the soil layer of 20～40cm,the urease activity increased by 11.94%～23.64%from spinning stage to maturity stage.The activity of alkaline phosphatase increased by 7.41%in the bell-opening stage.The activity of sucrase increased by 6.80%-25.81%from jointing stage to spinneration stage.Catalase activity increased by 2.33%at jointing stage.5.Under the condition of quantitative straw returning,the content of alkali-hydrolyzed nitrogen in 0-20cm soil layer was increased by 4.21%,6.52%and 7.64%at jointing,trumpet and mature stages,respectively,compared with that without straw returning.The content of available phosphorus increased by 9.56%at jointing stage.The content of available potassium increased by 9.05%and 15.15%at jointing and maturity stages,respectively.In the soil layer of 20～40cm,the content of alkali-hydrolyzable nitrogen increased by 4.06%～4.76%during the whole growth period.The content of available phosphorus increased by 10.54%～13.30%from jointing stage to bell-honking stage.