Study On Fertilizer Effect And Effects Of Interaction Between Fertilizer And Salt On Coastal Saline Soil And The Growth Of Winter Wheat

The saline soil in the Yellow River delta is widely distributed,and the land use efficiency is low due to the influence of salinity,soil structure and fertility.Salinity,the main obstacle factor,is extremely unfavorable for crop as the salinity is high.Reasonable application of fertilizer can slow down the salt stress on crops partly and reduce the risk of fertilizer waste and water eutrophication,which is beneficial to the improvement of inefficient agricultural development in coastal areas.At present,the interaction between fertilizer and salinity needs to be further strengthened.In order to obtain the best amount of economic fertilizer,it is necessary to establish the fertilizer effect model of winter wheat in the Yellow River delta.In this paper,effects of salinity and nitrogen in winter wheat seedling on soil physicochemical properties and winter wheat were discussed by controlling the salinity and nitrogen of pot experiment in the indoor arrangement.To investigate the effect on winter wheat and soil physicochemical properties in mild saline soil,"3414" experiment of nitrogen and phosphorus fertilization experiments was arranged at the same time.Finally,according to the mathematical model,nitrogen and phosphorus fertilizer effects on winter wheat yield was discussed through the "3414" test.The main research contents and conclusions are as follows:?1?Controlling levels of salinity and nitrogen?0.7,1.7,2.7 g/kg and 135,270405 kg/hm²?in pot experiment,the effects of soil physicochemical properties and winter wheat were investigated at seedling stage.The results showed that the dry weight of winter wheat was first promoted by salinity,but its growth was gradually inhibited by nitrogen fertilizer.The dry weight of shoot was affected by the salinity,later than the dry weight of the ground,and the inhibition of salinity was stronger than that of nitrogen fertilizer when it grew to 54 days.Total N of shoot and root of winter wheat was mainly affected by nitrogen,and when the amount of nitrogen was less than 270 kg/hm²,the content of total N increased with the increase of nitrogen application rate.Nitrogen affected the accumulation of total N in the shoot,and then affected the accumulation of total N in the ground.Increasing nitrogen fertilizer was helpful to saline soil improvement,which could reduce the soil pH increasing,and the higher salinity was,the lower the growth rate was.When the amount of nitrogen was below 270 kg/hm²,the total N in soil was directly proportional to the amount offertilizer.The NO₂^-and NO₃^-of soil were also affected by the nitrogen fertilizer,the content of which increased with the increase of nitrogen application rate.In the early growth stage?54 days?of winter wheat,the interaction of nitrogen and salinity showed significant effects on shoot dry weight,total N content and soil NO₂^-in winter wheat growing up to 33 days.When winter wheat was grown on saline soil less than 2.7g/kg,the amount of nitrogen fertilizer should be controlled at 270kg/hm²,so as to avoid excessive use of fertilizer and cause waste of fertilizer.?2?In the Yellow River Delta region,"3414" test of nitrogen and phosphorus was arranged.Controlling levels of nitrogen?0,135,270,405 kg/hm²?and phosphorus?0,53,105,157.5 kg/hm²?,the effects of soil physicochemical properties and biomass of winter wheat were investigated during the whole growth period of plant.The results showed that the yield of winter wheat could be increased by controlling nitrogen and phosphorus fertilizer on mild saline soil,and the effect of nitrogen fertilizer was higher than that of phosphate fertilizer.The yield of single nitrogen fertilizer was increased by 11.6%,and the yield of single application of phosphorus fertilizer was increased by 10.6%.When the amount of nitrogen and phosphorus were 270 and 105 kg/hm²,the yield of winter wheat reached 6339kg/hm²,and increased by 41.7%.The effects of nitrogen and phosphorus fertilizer on the physical and chemical properties of different soil layers and different soils are different.Nitrogen fertilizer mainly affected soil physical and chemical properties in0-20 cm soil layer,while phosphate fertilizer mainly affected soil physical and chemical properties?except available phosphorus?in 20-40 cm soil layer,and their influence period was concentrated before winter wheat filling period.The application of N and P fertilizer decreased the soil pH increase,and it was helpful to the improvement of saline soil.However,the excessive application of phosphate fertilizer could increase the risk of secondary salinization of soil.Applying nitrogen fertilizer helps increase soil NO₃^-content and helps crop uptake,but also increases the risk of nutrient loss.?3?Four fertilization models-linear plus plateau,unary quadratic,square root,and binary quadratic,were used to simulate the impact of nitrogen and phosphorus fertilizer on wheat yield to examine the suitable fertilization model for wheat grown on mathematical model in saline soil of Yellow River delta.The results suggested that these four fertilization models reached extremely significant level?p < 0.01?by fitting test.Unary quadratic model of N and P fertilizer was the best among the unaryfertilization models.On the base of the fitting degree,best economic fertilizer rate,agronomic efficiency of fertilizer,economic benefits and limitations of unary models,binary model was better compared with unary model.In binary model,the best N and P application amount were,respectively,244.1 kg/hm² and 94.2 kg/hm² with the ratio of N to P at 2.6.In this model,the economic benefit,the agronomic efficiency of N and P were 7432.4 yuan/hm²,6.2 kg grain/kg?N?and 13.8 kg grain/kg?P2O5?.According to the annual grain price and fertilizer price change,the model can be used to calculate the optimum economic fertilizer amount in the region,which can be applied to scientific guidance fertilization.