| Soil texture is an important determinant of the structure and fertility of coastal saline soil,and the application of soil conditioners is an important measure for rapid improvement of coastal saline soil.This study collected five soil textures(sandy loam,medium loam,heavy loam,light clay,and medium clay)under two types of land use(uncultivated and paddy soils)in coastal saline soil areas in Zhejiang Province,using the methods of soil biology,chemistry and physics to study the changes in soil fertility and microbial community structure diversity.The pot and field experiments were conducted to study the effects of different application rates of the mineral-based soil conditioners and different types of soil conditioners on the physical and chemical properties of coastal saline soil(p H,Ec,SOC,TN,AN,AK and AP),rice nutrient absorption and yield.The results would provide theoretical and technical basis for the rational application of soil conditioners and improving coastal saline soil.(1)Among the five texture soils,soil Ec,value,OC,TN,AN,AK,catalase activity,urease activity,bacterial PLFAs,actinomycetes PLFAs,Shannon-Ville diversity index,Evenness and Richness were significantly(P<0.01)positively correlated to soil clay content(<0.01mm),and significantly(P<0.01)negatively correlated to soil coarse silt content(0.01mm-0.05mm)and sand(0.05-0.25mm)content.On the contrary,soil p H and protease activity were significantly(P<0.01)negatively correlations with clay content,and significantly positively correlated to soil coarse silt sand and sand content,and AP content and fungal PLFAs were not significantly related to soil particles.Compared with uncultivated soil at the same soil texture,paddy soil significantly reduced soil p H,Ec,and AK content,but it significantly increased OC,TN,AN,AP,enzyme activity and microbial PLFAs.Soil texture and land use type had a significant(P<0.01)synergistic effect on the soil fertility and microbial community structure in coastal saline soil.(2)After applying the mineral-based soil conditioner(the rates of T1,T2,T3 and T4 were 5.0,7.5,10,and 12.5 g·kg-1 respectively),soil p H,Ec,and the content of AP were significantly reduced compared with the control,the content of OC,TN,AN,AP,and the content of rice straw and grain TN,TP and TK had a significant increase compared to the control treatment(CK,no soil conditioner).Application of 10g·kg-1 treatment(T3)had the best effect.Soil p H,Ec,and the content of AK in T3 were reduced by 7.1%,36.7%,and 19.7%,respectively,and OC,TN,AN,and AP in T3 were increased by 32.3%,41.7%,42.1%,40.6%,and TN,TP and TK in rice straw increased by 49.8%,49.7%and 36.2%,respectively,and the TN,TP and TK in the grains increased 33.1%,41.2%and 34.5%,Compared with the control(CK),rice grain yields of T1,T2,T3 and T4 increased by 9.2%,16.4%,18.6%,12.1%,respectively,and excessive application(T4 12.5 g·kg-1)had reduced soil fertility.(3)After applying different amounts of desulfurized gypsum and humic acid fertilizers,soil physical and chemical properties in the four stages of rice had been significantly improved.With the increase in the amount of desulfurized gypsum and humic acid fertilizers,soil p H,Ec,and AK content continued to decrease,but the contents of TN,OC,AN and AP increased accordingly.Meanwhile,desulfurized gypsum and humic acid fertilizers increased the effective grain number,thousand-grain weight and grain yield of rice.After applying different amounts of humic acid fertilizer,rice grain yield increased by 6.9%-13.5%compared to CK;after applying different amounts of desulfurized gypsum,rice grain yield increased by3.1%-8.2%compared to CK.However,when the application rate of desulfurization gypsum reached 10t·hm-2and the application rate of humic acid fertilizer reached 22.5 t·hm-2,soil fertility and rice grain yield began to decline.In summary,in order to effectively improve the coastal saline soil,the reasonable application rates of desulfurized gypsum and humic acid fertilizers are 7.5 t·hm-2 and 10 t·hm-2,respectively. |
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