Effect Of Biochar On Rape And Cotton Growth And Nutrient Efficiency On Different Soils

Biochar was a solid byproduct derived from biomass pyrolysis in low or zero oxygen environments. The research on biochar had great prospect in agriculture and environment because of its excellent characteristics, which was rich in nutrients of carbon and potassium especially, and alkaline to ameliorate acidic soil. This research was conducted to study the effect of single biochar on ameliorate soil of different acidity and fertility and crop growth, nutrient uptake firstly, furthermore to explore the effect combining application of biochar and fertilizer on cotton growth, nutrient use efficiency and the interaction of biochar-fertilizer on potassium deficient soil, aiming to provide a new effective approach for replacing potassium and high-efficiency utilization. The main results were as followed:1. Biochar improved dry matter accumulation and distribution of different rape organ and promoted the formation of rape production on two soils with different soil acidity and fertility(yellow brown soil with slightly acidic and high soil fertility and red soil with strongly acidic soils and poor fertility). The total dry matter weight and dry matter accumulation of roots, stems, leaves, pods and other organs of rape were significantly improved on yellow brown soil and red soils after adding1%biochar. Compared with other parts, the increase of rape yield on two different soils were most significant. The proportion of rape reproductive organs were increased by10.4%and245%on yellow brown soil and red soils, respectively.2. Biochar promoted N、P、K absorption of different rape organs on two soils with different soil acidity and fertility. After adding1%biochar, the N、P、K uptake of different rape organs on yellow brown soil and red soil were increased by68.4%,90%,118%and90%,354%and2853%, respectively.3. Biochar affected the properties of two different acidity and fertility soils. After adding1%biochar, pH and the contents of available P, available K and organic matter of yellow brown soil and red soil were significantly increased by0.33,0.74mg/kg,29mg/kg,6.9g/kg and0.54,1.89mg/kg,35.3mg/kg,7.4g/kg respectively, and the response of potassium on biochar was maximum. The influence of biochar on the red soil with strongly acidic soils and poor fertility was much better than the yellow brown soil with slightly acidic and high soil fertility. 4. Biochar with proper K fertilizer on potassium deficient soil promoted the growth of cotton plant height, squaring numbers, bolls numbers, and effective branches and increased the dry matter accumulation of the whole cotton and different organs and uptake of K、N、P, at the same time, improved the proportion of cotton reproductive organs. After combined application1%biochar and K fertilizer, cotton plant height increased by an average of16.5cm, the peak of squares numbers occurred12.6days in advance, the number of bolls numbers improved8-11, the number of bolls numbers increased11.8, the number of effective branches increased1.6. Biochar with proper K fertilizer on potassium deficient soil, After combined application1%biochar and K fertilizer, the increase of dry matter accumulation of leaves, bell and seed cotton were increased greater with120%,80.3%and103%respectively, the proportion of reproductive growth/total weight was increased by8.0%averagely. Biochar-K can improve the N、P、K uptake of different cotton organs, which affected the bell most, with an average of122%,105%and183%, respectively.5. Biochar-K increased harvest index, fertilizer contribution rate and K fertilizer utilization on potassium deficient soil. There were significant performance on the K fertilizer contribution rate and the fertilizer contribution rate was increased by50.5%averagely compared to the single fertilizer; there were significant influnence on the K fertilizer utilization under interaction of combined application biochar and K fertilizer, increased by9.4%compared to single fertilizer.6. Biochar-K improved the fertility and reduced acidity of potassium deficient soil. The soil pH increased by an average0.4-0.8units and active aluminum decreased14.0%after adding1%biochar. The contents of soil available K and organic matter were increased by an average of33%and51%compared to single fertilizer treatments. Biochar-K increased soil content of exchange calcium and magnesium.