The Effect Of Three Green Manures Crops Application On The PH Of Acid Yellow Earths And Alkaline Yellow-brown Earths In Gui Zhou

As a clean organic fertilizer source,green manure plays an important role in the development of sustainable agriculture.The research results of green manure in supplying soil nutrients,improving soil environmental quality,and increasing soil microbial activity have been widely application.But,related studies have shown that turnover green manure will change the pH of the soil.In order to ensure sustainable use of green manure in production,the acid yellow earths and alkaline yellow-brown earths in Guizhou Province were selected as the test soils.The pot experiment was used in the greenhouse of the Guizhou Academy of Agricultural Sciences.Research was conducted on the three common green manures in Gui Zhou Province,such as Brassicaceae green manure-Raphanus sativus L.,Leguminosae sp.green manure-Vicia villosa Rothvar,and Gramineae green manure-Lolium L.,and set three amount of overturning.Explored the changes of soil pH during the rapid decomposing period of green manure,and the interaction relationship between soil buffering performance,soil exchange performance,other soil chemical properties and soil pH during this period,with a view to discussing the effect of pressing three green manure crops on the pH value of acid yellow earths and alkaline yellow-brown earths in Gui zhou.The preliminary results of the research showed that:Different varieties of green manure,different amount of turning pressure and different decomposing time have different effects on the change of soil pH after turning green manure.In different soil types,with the decomposing time of green manure crops,the pH value of acid yellow earths first increased and then decreased,while the pH value of alkaline yellow-brown earths showed a downward trend as a whole.In terms of different green manure varieties and their turnover,Vicia villosa Rothvar can significantly increase soil pH when the amount of turning pressure is 150g/pot.,when the amount of turning pressure of Raphanus sativus L.and Lolium L is 250g/pot,it will increase the soil pH rapid decomposition day 18th.Under the same turning pressure,the three green manure crops can increase the soil pH to different degrees.The performance is:Vicia villosa Rothvar>Lolium L.>Raphanus sativus L.The pH value of the soil decreased after turning over green manure crops in alkaline yellow-brown soil,and the soil pH value was obviously lowered in 18th stage of rapid decomposing when the amount of turning pressure of Raphanus sativus L is 250g/pot was high.Vicia villosa Rothvar and Lolium L.will lower the soil pH in the 24th of rapid decomposition.The effect of green manure crops of different families on lowering the soil pH is as follows:Raphanus sativus L.>Vicia villosa Rothvar>Lolium L.In terms of soil buffering performance,turning over green manure crops all can improve the soil buffering performance.The effects of different varieties and different turning pressures on the soil buffering capacity in acid yellow earths are as follows Lolium L.>Raphanus sativus L.>Vicia villosa Rothvar.In alkaline yellow-brown soil,the effect of soil buffering capacity is as follows:Vicia villosa Rothvar.>Lolium L.>Raphanus sativus L.;in addition,correlation analysis found that soil buffering performance has little effect on soil pH.In trems of soil exchange performance,the pH value of acid yellow earths gradually increases with the decrease of soil exchangeable H⁺and Al³⁺content after turning over green manure crops,correlation analysis shows that the increase of soil exchangeable acid content will significantly affect the increase of soil pH.Regression analysis shows that the decrease of soil exchangeable H⁺content has a higher impact on the change of soil pH than the increase of soil exchangeable Al³⁺content.After green manure crops are turnovered,the pH value of acid yellow earths gradually increases with the increase of soil exchangeable base ion content.Correlation analysis and regression analysis show that the increase of soil exchangeable K⁺,Na⁺,Ca²⁺,Mg²⁺content will significantly affect the increase of soil pH value,the influence of the content of the four soil exchangeable base ions on the change of soil pH value was K⁺>Ca²⁺>Na⁺>Mg²⁺.The pH value of alkaline yellow-brown earths gradually decreases with the decrease of soil exchangeable Ca²⁺,Mg²⁺,and K⁺content.Correlation analysis and regression analysis show that the decrease of soil exchangeable Ca²⁺,Mg²⁺,K⁺content will significantly affect the decrease of soil pH value.The degree of influence of the content of exchangeable base ions in the soil on the change of soil pH is in the order of Ca²⁺>K⁺>Mg²⁺.In terms of other chemical properties of the soil,the pH value of acid yellow earths after pressing green manure crops has a decreasing trend with the increase of soil NO₃^--N,NH₄⁺-N,organic matter,humic acid,and fulvic acid content.Correlation analysis and regression analysis show that the increase in soil NO₃^--N,NH₄⁺-N,organic matter,humic acid,and fulvic acid content will significantly affect the increase of soil pH,the order of influence is NH₄⁺-N>humic acid>organic matter>fulvic acid>NO₃^--N;In alkaline yellow-brown earths,the soil pH value decreases with the increase of soil NO₃^--N,organic matter,and fulvic acid content,and with the decrease of soil NH₄⁺-N content,the change of soil humic acid content on pH value the impact is not significant.Correlation analysis and regression analysis show that the increase of soil NO₃^--N,organic matter and fulvic acid content will significantly affect the decrease of soil pH,and the order of influence is organic matter>NH₄⁺-N>fulvic acid>NO₃^--N.In summary,the pH value of yellow earths and yellow-brown earths is affected by the variety of green manure crops,the amount of turning pressure,the decomposing time,soil exchange performance,and the soil organic matter,humus and soil inorganic nitrogen content.During the rapid decomposing period,with the increase in the amount of green manure crops and the decomposing time of the green manure crops,the pH value of yellow earths has a tendency to increase first and then decrease.Soil organic matter and ammonium nitrogen content have a greater impact on the pH changes of yellow earths and yellow-brown soil.The transformation of soil nitrogen and the increase of soil organic matter are the main factors that affect the change of soil pH after green manure is overturned,but in different soil types the law of performance is different.