| High and stable forage production and sustainable use of cropland are important for the development of grassland animal husbandry in karst mountainous areas.The introduction of cover crops to fill the winter idle period can make full use of land resources to produce high-quality forage,improve soil nutrient conditions constrained by phosphorus,and support nutrient supply for subsequent crops with conservation tillage measures.However,the effects of winter cover crop use on the productivity of subsequent crops and soil phosphorus under different tillage practices still need to be further clarified.To this end,this study was conducted in a field trial of hairy cropsilage maize in Sinan County,Tongren City,Guizhou Province,to investigate the nutrient release transfer characteristics of different tillage practices(no-till and conventional tillage)and different utilization methods of cover crops(root stubble return,cover return,tilled return,and live covering)and their effects on the yield quality and soil phosphorus fraction of silage maize.The main findings were as follows:1.The effects of different tillage methods on the yield of hairy vetch,soil nutrients,crop decomposition and phosphorus nutrient release.The first and second mowing yields of maize under no-till were 15.6 % and 15.4 %lower,respectively,compared to the tillage treatment(P < 0.05),while the third mowing yield increased by 20 % compared to the tillage treatment,and the crude protein content of maize under no-till treatment increased by 18 % compared to tillage at the second mowing;the decomposition rate of tilled pressure was higher than that of mulched return after 14 days,and after 49 days,there was no significant difference between the return methods.The phosphorus nutrient release was significantly higher from 14 to 28 days after tillage than after mulching,and no significant difference was observed after56 days.2.Effects of cover crop utilization on yield,economic benefit and energy budget of silage maize.The highest silage yield(P < 0.05)was achieved in the tillage cover treatment,which was 29 % higher compared to the control tillage recreation treatment.Compared to the control,the no-till measure significantly increased crude protein content(P <0.05)and the net energy value of the tillage mulching treatment increased by 35 %compared to the control treatment;in terms of economic benefits,the tillage mulching,tillage,no-till mulching and no-till live mulching treatments had higher returns,increasing by 40 %,36 %,37 % and 31 %,respectively,compared to the tillage recreational treatment.3.Effects of mulching crop utilization on soil phosphorus fractions.The water-soluble phosphorus content of the no-till live mulch treatment was significantly higher by 102 %(P < 0.05)compared with the tillage recreation treatment in the 0-30 cm soil layer,the total phosphorus content of the sodium bicarbonate leaching state was 356 % higher in the no-till mulch treatment compared with the tillage recreation,the inorganic phosphorus content of the sodium hydroxide leaching state and the total phosphorus content were higher in the tillage with other mulching methods than in the no-tillage treatment,and the sodium hydroxide leaching state phosphorus content was higher in the tillage recreation treatment than in the no-tillage treatment.The phosphorus content of the leaching state accounted for 23 % of the phosphorus fraction in the tillage recreation treatment,and the phosphorus content of the leaching state of hydrochloric acid was 63 %.The comprehensive analysis concluded that no-till mulch return to the field had low decomposition rate and nutrient release rate,delayed the peak of decomposition nutrient release from cover crops,and effectively controlled the greedy green growth of silage maize at the seedling stage.No-till mulch return improved silage maize yield,quality,net energy value and economic efficiency,while effectively increasing soil water-soluble phosphorus content,with good ecological and economic benefits. |
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