| In order to meet the demand for food for population growth,fertilizer input has become the main means of increasing crop yields in agricultural production.However,excessive and unreasonable fertilization methods can lead to underutilization of nitrogen,phosphorus and potassium fertilizers.Moreover,the quality of the soil and water environment has been seriously damaged,which has led to the growing problem of agricultural non-point source pollution.As a kind of high-quality organic fertilizer resource with wide source and fertilization,crop straw and livestock manure can not only fertilize the soil,but also provide organic and inorganic nutrients for crops.At the same time,it can also realize the recycling of waste,and can also reduce the input of chemical fertilizers.According to a certain proportion,replacing some chemical fertilizers with organic fertilizer can effectively alleviate the slow release rate of organic fertilizer nutrients,and coordinate the fertilizer supply process to meet the demand for nutrients.It is an important guarantee for the sustainable development of moden agriculture in China.This study carried out field positioning experiments in the Chaohu Basin from November 2017 to June 2018.Studied the effects of different organic fertilizers on the ratio of chemical fertilizers to rice-wheat yield and its components,crop nutrient uptake,fertilizer utilization,soil nutrient and nitrogen and phosphorus loss from farmland surface runoff.The main findings are as follows:(1)Compared with single application of chemical fertilizer,30%and 50%of pig manure organic fertilizer instead of chemical fertilizer treatment can ensure crop yield increase or no yield reduction.The yields of wheat and rice were the highest under the treatment of 30%and 50%pig manure organic fertilizer instead of chemical fertilizer,which were 5505.29 kg/hm2 and 10439.66 kg/hm2,respectively.The yield of rice and wheat treated by pig manure organic fertilizer instead of chemical fertilizer was higher than that of straw organic fertilizer.(2)Organic fertilizer can significantly increase the absorption of nitrogen and phosphorus nutrients in crops.The absorption of nitrogen and phosphorus generally decreases with the increase of the proportion of organic fertilizer application in the wheat season.In the rice season,30%and 50%organic fertilizers replaced fertilizers,and nitrogen and phosphorus uptake were significantly increased.However,100%organic fertilizer treatment decreased significantly due to crop yield,and nitrogen and phosphorus nutrient accumulation decreased accordingly.Compared with straw organic fertilizer treatment,pig manure organic fertilizer treatment is more conducive to nitrogen and phosphorus nutrient accumulation in wheat and rice.(3)In the wheat season,the utilization rate of nitrogen and phosphorus fertilizers treated with 30%organic fertilizer instead of chemical fertilizers was significantly higher than that of single application of chemical fertilizers.In the rice season,the utilization rate of nitrogen fertilizer is between 18.03%and 42.06%,and the utilization rate of phosphate fertilizer is between 3.7%and 23.59%.Compared with the wheat season,50%and 100%organic fertilizer instead of chemical fertilizer treatment increased nitrogen and phosphorus utilization.The utilization rate of nitrogen and phosphorus fertilizers gradually decreases with the increase of the proportion of organic fertilizer application.(4)The replacement of chemical fertilizer with organic fertilizer significantly promoted the contents of soil organic matter,available phosphorus and available potassium.The treatment effect of 100%organic fertilizer was the most significant.In addition,the treatment of pig manure organic fertilizer instead of chemical fertilizer was more conducive to improving soil nutrient content..(5)The replacement of chemical fertilizer by organic fertilizer can reduce the nitrogen concentration in the field and reduce the potential risk of nitrogen loss in rice fields,effectively.The average concentration of NH4+-N,NO3--N,total nitrogen(TN)and total phosphorus(TP)treated by single fertilizer application was significantly higher than that of organic fertilizer instead of chemical fertilizer.And with the increase of the proportion of organic fertilizer application,the concentration of nitrogen and phosphorus gradually decreased,and the concentrations of TN and TP in the surface water of pig manure organic fertilizer and straw organic fertilizer were roughly the same.(6)The single fertilizer application treatment of runoff water TN loss was the highest in wheat and rice season,and the loss and 1oss rate of TN decreased in turn with the increase of organic fertilizer application rate.The loss of TN from pig manure organic fertilizer instead of chemical fertilizer is slightly higher than that of straw organic fertilizer.The loss and loss rate of TP in wheat and rice season increased with the replacement of 100%,30%and 50%organic fertilizers. |
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