| In order to provide a theoretical basis for the development of regional agriculture with high quality,this paper studied the nutrient resource utilization,soil and water conservation effects and annual production and investment benefits of main grain and oil planting modes in hilly areas of Sichuan.In Xiangtan Village,Cangshan Town,Zhongjiang County,Deyang City,Sichuan Academy of Agricultural Sciences,a 2-year field runoff monitoring site was used to conduct a comparative study on winter wheat/spring maize/sweet potato(CK),winter wheat/spring maize/soybean(wheat/maize/bean),potato/spring maize/soybean(potato/maize/bean),winter wheat-summer maize(wheat-maize)and Rapeseed-summer maize(cole-maize).The effects of five planting modes on annual biomass accumulation,N,P,K nutrient uptake and nutrient balance utilization efficiency,surface runoff and sediment loss,annual grain yield and production-input benefit of crops.The results show that:(1)The average annual biomass accumulation in two years was winter wheat/spring maize/sweet potato>wheat-maize>potato/maize/bean>cole-maize>wheat/maize/bean;The annual straw biomass of wheat/maize/sweet potato was the highest,followed by wheat-maize>cole-maize>wheat/maize/bean>potato/maize/bean;The biomass accumulation of annual harvest was wheat/maize/sweet potato>potato/maize/bean>wheat-maize>cole-maize>wheat/maize/bean.The results showed that the wheat/maize/sweet potato model had biomass advantages.(2)Under different planting patterns,the total nutrient uptake of crops was K(290.23-403.53kg/hm~2)>N(271.62-367.76kg/hm~2)>P(58.36-93.00 kg/hm~2);K uptake by crop straw was(160.79-292.30 kg/hm~2)>N(89.13-163.26 kg/hm~2)>P(15.46-36.38 kg/hm~2);The accumulative uptake of nutrients by harvesters was N(162.24-232.70 kg/hm~2)>K(40.88-137.63 kg/hm~2)>P(42.89-58.20kg/hm~2).Among the treatments,wheat/spring maize/sweet potato had the highest nitrogen uptake,potato/maize/bean,wheat/maize/bean,cole-maize and wheat-maize decreased by 12.49%,18.30%,26.14%and 26.03%respectively;The total nitrogen uptake of straw was highest in wheat/spring maize/sweet potato,followed by cole-maize,and lowest in wheat/maize/bean;Nitrogen uptake of the harvest was wheat/maize/bean>potato/maize/bean>wheat/spring maize/sweet potato>wheat-maize>cole-maize.The total phosphorus uptake by crops was wheat/spring maize/sweet potato>wheat/maize/bean>potato/maize/bean>cole-maize>wheat-maize,which decreased by 28.08%,26.05%,24.32%and 20.07%respectively;The regularity of phosphorus uptake by straw was wheat/spring maize/sweet potato>potato/maize/bean>cole-maize>wheat/maize/bean>wheat-maize;The phosphorus accumulation of wheat/maize/bean was the highest,and the others were wheat/spring maize/sweet potato>potato/maize/bean>cole-maize>wheat-maize.The total annual potassium uptake of crops was wheat/maize/potato>cole-maize>wheat-maize>potato/maize/bean>wheat/maize/bean,which was 28.08%,26.05%,24.32%and 20.07%lower than that of the control,respectively;The accumulation regularity of potassium in straw was heat/maize/potato>wheat/maize/bean>cole-maize>wheat-maize>potato/maize/bean,which was 22.59%,44.99%(p<0.05),11.01%and 3.63%lower than the control,respectively;The potassium uptake of the harvest was potato/maize/bean>wheat/maize/potato>wheat/maize/bean>wheat-maize>cole-maize.In summary,the total N and P uptake of the three-cropping model was higher than that of the second-cropping model,and the total K uptake of the three-cropping model was higher than that of the wheat/maize/bean and potato/maize/bean models except wheat/spring maize/sweet potato;Among them,wheat/spring maize/sweet potato model had the highest total absorption of nitrogen,phosphorus and potassium.Nitrogen and phosphorus nutrient distribution showed that the harvest was higher than the straw,while potassium uptake showed that the straw was higher than the harvest.Under different planting patterns,the fertilizer use efficiency(PNB)of nutrient balance method was potassium>nitrogen>phosphorus.The nitrogen balance utilization efficiency of wheat/spring maize/sweet potato was the highest,which was 2.07%,8.58%,33.25%and 33.15%higher than that of wheat/maize/bean,potato/maize/bean,wheat-maize and cole-maize respectively;The highest P balance utilization rate was wheat/maize/bean,followed by potato/maize/bean,wheat/spring maize/sweet potato,cole-maize,wheat-maize;The balanced utilization efficiency of wheat/jade/vetch potassium was the highest,which was 1.11%,9.61%,16.75%and 12.07%higher than that of wheat/maize/bean,potato/maize/bean,wheat-maize and cole-maize,respectively.(3)The total annual surface runoff was wheat/spring maize/sweet potato>potato/maize/bean>wheat-maize>wheat/maize/bean>cole-maize,which decreased by 11.55%,14.08%,21.74%(p<0.05)and 26.05%(p<0.05)respectively compared with the control.It shows that the oil-jade model has a good effect on intercepting surface runoff.(4)The average annual grain yield of two years was wheat/spring maize/sweet potato,followed by potato/maize/bean,wheat-maize,cole-maize,wheat/maize/bean.The annual grain yield of different planting patterns in 2017 was 13.21%,33.64%(p<0.05),46.72%(p<0.05)and 50.43%(p<0.05),respectively,lower than that of the control;The grain yield of wheat/spring maize/sweet potato model in 2018 was 22%(p<0.05),24%(p<0.05),3%and 1%lower than that of wheat/maize/bean,potato/maize/bean,wheat-maize and cole-maize.It shows that wheat/spring maize/sweet potato model is helpful to ensure regional food security.(5)The annual output value of potato/maize/bean was the highest,which was 16.63%,37.49%,54.45%and 37.27%higher than that of wheat/spring maize/sweet potato,wheat/maize/bean,wheat-maize and cole-maize,respectively.The annual production cost of wheat/maize/potato treatment was the highest,followed by potato/maize/bean>wheat/maize/bean>wheat-maize>cole-maize.The final economic benefit and output-input ratio of potato/maize/bean was the highest,reaching 5633.82yuan/hm~2,and the wheat-maize model lost 2315.01 yuan per hectare.In summary,in the hilly areas of Sichuan,wheat/spring maize/sweet potato under the decentralized management mode belongs to the high-cost,high nutrient demand and high-yield mode;The annual output value and benefit of potato/maize/bean model are the highest.Under the condition of scale management,the nutrient of wheat-maize model can effectively reduce the occurrence of surface runoff and soil erosion;The economic benefit of cole-maize is high(3222.72 yuan/hm~2). |
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