Effects Of Chemical Fertilizer Reduction And Partial Substitution On Growth And Nutrient Utilization Of Rice

In the process of traditional rice production,a large amount of chemical fertilizer is often put in,which not only reduces the utilization rate of fertilizer,but also causes environmental pollution and affects the sustainable development of rice industry.In order to explore the technical way of chemical fertilizer reduction in double cropping rice region of South China,field experiments on chemical fertilizer reduction of rice were carried out in 2019,in which seaweed extract and microbial inoculant were used to replace chemical fertilizer.Seaweed extract and microbial inoculant to partly replace nitrogen fertilizer on rice growth and nutrient uptake experiment was conducted in Binyang County,Liucheng county and Beiliu City of Guangxi Province in 2019.Five fertilization measures were set up,including conventional nitrogen rate(T1),conventional nitrogen rate + seaweed extract and microbial inoculant(T2),-20% nitrogen fertilizer + seaweed extract and microbial inoculant(T3),-30% nitrogen fertilizer + seaweed extract and microbial inoculant(T4),-40% nitrogen fertilizer + seaweed extract and microbial inoculant(T5).In the experiment of rice growth and nutrient absorption and utilization,seaweed extract and microbial inoculant partially replaced chemical fertilizer(including nitrogen,phosphorus and potassium),four treatments were set up: conventional fertilizer amount(P1),-10%chemical fertilizer + seaweed extract and microbial inoculant(P2),-20%chemical fertilizer + seaweed extract and microbial inoculant(P3),-30%chemical fertilizer + seaweed extract and microbial inoculant(P4).The leaf area index,dry matter accumulation,yield and yield components,nitrogen,phosphorus and potassium uptake of rice were determined.The main results are as follows:1.Effects of seaweed extract and microbial inoculant replacing part of nitrogen fertilizer on growth and yield of rice.Compared with T1,the leaf area index of rice was increased by adding seaweed fertilizer and microbial inoculant;the dry matter accumulation and yield of T2 and T3 were increased by 6.63%,1.43% and 4.24%,3.31% respectively compared with T1;The effective panicles,grains per panicle,filled grain rate and 1000-grain weight of T3 were increased by 0.64%,3.79%,4.68%,0.45% respectively compared with T1.In the reduced fertilization treatment,20% nitrogen fertilizer combined with seaweed extract and microbial inoculant(T3)could improve the dry matter accumulation,yield and yield components of rice.2.Effects of seaweed extract and microbial inoculant replacing part of nitrogen fertilizer on nutrient absorption and utilization.The nitrogen uptake of rice was promoted by adding seaweed extract and microbial inoculant.The accumulation of T2 nitrogen was 2.76% higher than CK.The nitrogen dry matter production efficiency,nitrogen grain production efficiency,nitrogen harvest index and nitrogen partial foctor productivity of T3 increased by 7.42%,7.23%,0.87% and 29.14% respectively.In the reduced fertilization treatment,20% nitrogen fertilizer combined with seaweed extract and microbial inoculant(T3)could improve the nutrient use efficiency of rice.3.Under the condition of nitrogen reduction combined with seaweed extract and microbial inoculant,the yield of rice was significantly positively correlated with leaf area index,dry matter accumulation and effective panicles,and was positively correlated with filled grain rate and harvest index;Nitrogen accumulation,nitrogen harvest index and nitrogen partial factor productivity were significantly positively correlated with yield,while nitrogen dry matter production efficiency was significantly negatively correlated with yield..4.Effects of seaweed extract and microbial inoculant on growth and yield of rice.The dry matter accumulation and yield of P2 were 6.06%and 0.45% higher than CK(P1),and the grain per panicle,filled grain rate and harvest index of P2 were 4.36%,8.07% and 5.03% higher than CK,respectively.Reducing 10% of chemical fertilizer combined with seaweed extract and microbial inoculant(P2)can promote the accumulation of dry matter,improve yield components and rice yield.5.The effect of replacing part of chemical fertilizer with seaweed extract and microbial inoculant on nutrient absorption and utilization.The nitrogen / phosphorus accumulation,nitrogen / phosphorus / potassium dry matter production efficiency,nitrogen phosphorus potassium rice production efficiency and nitrogen harvest index of P2 treatment were increased by 0.75%,5.14%,5.04%,1.31%,2.18%,10.08%,6.66%,8.97%and 1.59%,respectively.The partial factor productivity of N P K fertilizer increased with the decrease of chemical fertilizer application,and the partial factor productivity of P4 treatment was the largest.Considering the comprehensive effects of different fertilization measures on rice growth,yield,nutrient absorption and utilization,and environmental health,reducing 20% nitrogen fertilizer or 10% chemical fertilizer combined with seaweed extract and microbial inoculant is a more scientific and reasonable fertilization measure in this experiment.