遮阴下滴灌施肥对小粒种咖啡土壤质量和水分利用的影响

Effects of drip fertigation under shade on soil quality and water use of Coffea arabica

【目的】探究遮阴下不同水肥耦合模式对小粒种咖啡根区土壤质量及水分利用的影响。【方法】以小粒种咖啡为研究对象,在30%遮阴度下,试验设2因素(灌水和施肥)3水平完全设计,共9个处理。3个灌水水平:高水(W_(H):1.2 Ep)、中水(W_(M):1.0 Ep)和低水(W_(L):0.8 Ep);3个施肥水平:高肥(FH:530.00 kg·hm^(−2))、中肥(F_(M):353.33 kg·hm^(−2))和低肥(FL:176.67 kg·hm^(−2))。分析小粒种咖啡根区土壤养分、微生物数量、酶活性、干物质量及灌溉水分利用效率对水肥调控的响应规律,通过隶属函数和因子分析相结合对土壤质量进行综合评价,再以TOPSIS法综合分析,找出小粒种咖啡最佳水肥耦合模式。【结果】灌水水平和施肥水平对小粒种咖啡根区土壤养分、微生物数量、酶活性(除秋季过氧化氢酶)、根干物质量、树干干物质量、总干物质量和灌溉水分利用效率影响显著。FHW_(L)处理的硝态氮、速效磷和速效钾含量季均值最高;F_(M)W_(H)处理的土壤微生物数量和酶活性季均值最高。与FLW_(L)处理相比,FHW_(L)处理的土壤硝态氮、速效磷和速效钾含量季均值分别增加72.61%、154.01%和7.37%,F_(M)W_(H)处理的土壤细菌、真菌和放线菌数量季均值分别增加121.81%、61.73%和41.43%,且脲酶、过氧化氢酶和磷酸酶活性季均值分别增加46.67%、42.74%和22.55%。土壤硝态氮含量与过氧化氢酶活性存在显著正相关;土壤细菌、真菌和放线菌数量分别与脲酶、过氧化氢酶和磷酸酶活性存在显著正相关。隶属函数和因子分析相结合的方法表明,F_(M)W_(H)处理土壤质量指数最高(0.75)。F_(M)W_(H)处理的总干物质量(38011.50 kg·hm^(−2))最大,F_(M)W_(L)处理的灌溉水分利用效率(7.88 kg·m^(−3))最大。TOPSIS法表明,F_(M)W_(M)处理的土壤质量、干物质和灌溉水分利用效率综合效益排名第1,其次是F_(M)W_(H)处理。【结论】在30%遮阴度下,F_(M)W_(M)处理为改善土壤质量且促进小粒种咖啡高效生产的最佳水肥耦合模式。

【Objective】To explore the effects of different coupling modes of water-fertilizer on root zone soil quality and water use of Coffea arabica under shade.【Method】C.arabica was chosen as test material,under 30%shading degree,three irrigation levels(WH:1.2 Ep,W_(M):1.0 Ep,W_(L):0.8 Ep)and three fertilization levels(FH:530.00 kg·hm^(−2),F_(M):353.33 kg·hm^(−2),FL:176.67 kg·hm^(−2))were completely designed with a total of nine treatments.The response laws of soil nutrient,microbial quantity,enzyme activities,dry mass and irrigation water use efficiency in root zone of C.arabica to water-fertilizer regulation were analyzed,and soil quality was comprehensively evaluated by combining membership function with factor analysis,and then the optimal water-fertilizer coupling mode of C.arabica was found by TOPSIS comprehensive analysis.【Result】Irrigation level and fertilization level had significant effects on soil nutrient,microbial quantity,enzyme activities(except catalase in autumn),root dry mass,stem dry mass,total dry mass and irrigation water use efficiency of C.arabica root zone.The average seasonal values of nitrate nitrogen,available phosphorus and available potassium contents in FHW_(L) treatment were the highest.The average seasonal values of soil microorganism quantity and enzyme activities were the highest in F_(M)WH treatment.Compared with FLW_(L) treatment,FHW_(L) treatment increased the average seasonal values of soil nitrate-nitrogen,available phosphorus and available potassium contents by 72.61%,154.01%and 7.37%,respectively;F_(M)WH treatment increased the average seasonal values of soil bacteria,fungi and actinomycetes number by 121.81%,61.73%and 41.43%,respectively,and increased the average seasonal values of urease,catalase and phosphatase activities by 46.67%,42.74%and 22.55%,respectively.There was a significant positive correlation between soil nitrate nitrogen content and catalase activity.The number of soil bacteria,fungi and actinomycetes were significantly positively correlated with the activities of urease,catalase and phosphatase,respectively.The combination of membership function and factor analysis showed that soil quality index of F_(M)WH treatment was the highest(0.75).The total dry mass(38011.50 kg·hm^(−2))of F_(M)WH treatment was the highest,and the irrigation water use efficiency(7.88 kg·m^(−3))of F_(M)W_(L) treatment was the highest.However,TOPSIS method showed that the comprehensive benefit(soil quality,dry matter and irrigation water use efficiency)of F_(M)W_(M) treatment ranked the first,followed by F_(M)WH treatment.【Conclusion】Under 30%shading degree,F_(M)W_(M) treatment was the best coupling mode of water-fertilizer for improving soil quality and promoting efficient production of C.arabica.