Effects Of Combined Application Of Organic And Inorganic Fertilizers On Crop Growth And Quality In Rice-lolium Multiflorum Rotation System

The combination of planting and breeding is the most ideal way to utilize and control the manure.Through the combination of planting and breeding,the waste of livestock and poultry can be safely and effectively treated to make organic fertilizer,and the waste can be turned into treasure.In addition,China's cultivated land resources are tight,the conflict between human beings and livestock for grain and land is prominent,and the forage resources for herbivorous livestock are seriously lacking.A large amount of roughage needs to be imported from home and abroad every year.Not only does the cost of forage increase,moreover,the low roughage self-sufficiency rate is not conducive to the sustainable and stable development of livestock industry.In order to produce high quality forage under rice and Lolium multiflorum rotation,the production of Lolium multiflorum was introduced into the main rice production areas in southern China,and organic fertilizer was used as an essential element in the production of forage crops,solve the farm sewage treatment problem and livestock coarse feed annual supply problem,so that the real organic combination of farming and aquaculture,to build green circular agriculture.The effects of combined application of organic and inorganic fertilizers on crop yield,nitrogen use efficiency,forage quality,silage quality,heavy metal content in crops and soil in rice-lolium multiflorum rotation system were studied by field experiments,the effects of different organic and inorganic fertilizers on crop growth,nitrogen use efficiency,forage quality and silage quality,heavy metal content and accumulation in rice-lolium multiflorum rotation system were studied,it provides scientific basis for fertilization and high efficient production of forage crops in rice-straw rotation system in South China.The experiment was conducted in Lishui plant experimental base of Nanjing,Jiangsu Province,and the design included 6 treatments:CK(no fertilizer),0%of(100%N from chemical fertilizer),25%of(25%N from organic fertilizer),50%of(50%N from organic fertilizer);75%of(75%N from organic fertilizer)and 100%of(100%N from organic fertilizer).The main results obtained were listed as follows.1.The results of two consecutive years showed that the yield of rice straw increased by11.13%and 5.69%,and the aboveground biomass increased by 7.06%and 4.52%respectively in the first and second years,however the difference of rice yield in the first year was not significant,but the rice yield in the second year increased by 3.84%.Compared with pure chemical fertilizer treatment,25%organic fertilizer substitution,the annual dry matter yield of Lolium multiflorum increased by 4.59%and 9.13%respectively in the first and second years.Compared with pure chemical fertilizer treatment,25%organic fertilizer substitution increased the total bioaccumulation of Lolium multiflorum and rice by 5.20%,but the yield difference was not significant under 50%organic fertilizer substitution treatment.2.Compared with pure chemical fertilizer treatment,25%organic fertilizer substitution treatment significantly increased nitrogen use efficiency of rice,among which nitrogen accumulation increased by5.26%and 19.04%,and the partial productivity of nitrogen fertilizer increased by 4.12%and 24.51%,and the agronomic efficiency of nitrogen fertilizer increased by 10.09%and 32.52%respectively in the first and second years respectively.The amount of nitrogen absorbed by stem,sheath,leaf and panicle was significantly correlated with the corresponding yield under different fertilization treatments.Compared with the pure fertilizer treatment,the nitrogen accumulation and apparent nitrogen use efficiency of Lolium multiflorum in the first and second years were increased by 17.75%and 16.30%,16.71%and 18.86%respectively.There was significant correlation between nitrogen uptake and yield of lolium multiflorum under different fertilization treatments.3.Compared with pure fertilizer treatment,the contents of crude protein,water-soluble carbohydrate,starch and non-structural carbohydrate in stem,sheath and leaves at heading stage,flowering stage and mature stage increased firstly and then decreased with the proportion of organic fertilizer applied,the dry matter digestibility in vitro,the content of acid detergent fiber and neutral detergent fiber had little change.The feeding quality and silage quality of rice straw treated with 25%of were the best.The feeding quality and silage nutritional quality of rice straw treated with high proportion organic fertilizer(50%-100%)were worse than those treated with pure fertilizer,but the fermentation quality of silage was better.4.The forage quality of stubble grass and regenerated grass of Lolium multiflorum was the best under 25%organic fertilizer,the contents of crude protein,water-soluble carbohydrate,starch,non-structural carbohydrate and in vitro dry matter digestibility of stems and leaves at heading and flowering stage were significantly higher than those of other treatments,but the content of neutral and acid detergent fibers was lower than that of other treatments.There was no significant difference in crude protein dry matter yield and digestible dry matter yield between 50%organic fertilizer and pure fertilizer,however,when the proportion of organic fertilizer application increased to 75%or more,the forage quality of lolium multiflorum decreased significantly.25%and 50%organic fertilizer were used to improve the nutritional quality and fermentation quality of ryegrass silage,and more than50%organic fertilizer was used to decrease the nutritional quality,but the fermentation quality was good.5.Cu,Zn and Cd in soil and plants increased with the proportion of organic fertilizer application,but all of them did not exceed the national safety limit.The contents of Cu,Zn and Cd in soil were higher in rice season than that in Lolium multiflorum season.The accumulation ability of heavy metals in different parts of rice and Lolium multiflorum was different.The contents of Cu,Zn and CD in soil were positively correlated with the contents of heavy metals in plants.Conclusion:The yield and nitrogen use efficiency of rice and lolium multiflorum could be improved by applying proper proportion of organic and inorganic fertilizer.The appropriate proportion of organic and inorganic fertilizer can promote the accumulation of crude protein,soluble carbohydrate,starch and other nutrients in the stem,sheath and leaves of the plant,the forage quality and silage quality of forage grass were improved.Combined application of organic and inorganic fertilizers promoted the accumulation of Cu,Zn and Cd in different parts of soil and plants.In the rice-Lolium multiflorum rotation system in the Yangtze Plain region,the effect of replacing 25%-50%chemical nitrogen fertilizer with organic fertilizer was the best under the condition of conventional nitrogen application(225kg/hm~2 for rice and 225 kg/hm~2 for Lolium multiflorum).