微灌方式耦合施肥水平对土壤质量、芒果幼树生长和水肥利用效率的影响

Optimum coupling of micro-irrigation method and fertilization level on soil quality,young mango tree growth and water-fertilizer use efficiency

【目的】通过研究芒果土壤微环境和生长特性对不同水肥耦合模式的响应,确定芒果幼树的最优微灌方式耦合施肥量。【方法】以2年生芒果幼树(品种为贵妃芒)为供试材料,在云南昆明理工大学大棚内进行完全随机组合设计田间试验,设置3种微灌方式:微喷灌(SI)、滴灌(DI)、微润灌(MI),和4个施肥水平:0、93.2、186.4、279.6 kg/hm2(依次标记为F0、F1、F2、F3)。每次灌溉施肥处理后30天(灌水后第3天),在距树干5~10 cm灌水器一侧采集土壤样品,测定芒果幼树根区土壤养分含量、酶活性、微生物数量,测量果树生长指标,计算水肥利用效率,并采用隶属函数结合因子分析法对芒果幼树土壤质量和生长质量进行综合评价。【结果】微灌方式和施肥水平对芒果幼树根区土壤养分含量(硝态氮、速效磷和速效钾)、酶活性(过氧化氢酶、脲酶和磷酸酶)、微生物数量(细菌、真菌和放线菌)、形态生长增量(株高、地径、叶片数和冠幅)、根系生长(总长度、表面积、体积和平均直径)和水肥利用效率影响显著(P<0.05)。同一施肥水平下,土壤微环境养分含量在3种灌溉方式间无显著差异,酶活性和微生物数量平均值均为MI>DI>SI,DI、MI土壤酶活性较SI分别增加了15.09%~26.57%和26.56%~48.86%,微生物数量分别增加了11.46%~30.19%、12.87%~42.45%,灌溉水利用效率(IWUE)分别提高了43.27%、73.17%,肥料偏生产力(PFP)分别升高了33.96%、54.44%。MI处理芒果的株高增量和根系体积的增幅最大,较SI分别显著增加了100.29%、54.06%。土壤过氧化氢酶活性、脲酶活性、微生物数量以及IWUE均在F2水平获得最大值,而土壤养分含量和土壤磷酸酶活性随施肥量的增加而升高,PFP则随之降低。相关性分析结果表明,土壤养分含量、酶活性、微生物数量与芒果生长指标之间均呈正相关关系,且相关程度依次递增。隶属函数结合因子分析结果表明,土壤质量综合指数(SQI)和芒果生长质量指数(GQI)均在MIF2条件下获得最大值。【结论】微润灌耦合施肥水平186.4 kg/hm2(MIF2组合)为改善土壤质量并促进芒果幼树生长的最佳灌溉施肥耦合方式。

【Objectives】The coupling effect of micro-irrigation method and fertilizer application rate for young mango trees was studied.【Methods】A field experiment was conducted in greenhouse of Kunming University of Science and Technology,using 2-year-old young mango tree‘Guifeimang’as experimental material.The 12 treatments were composed of three micro-irrigation methods:micro-sprinkler irrigation(SI),drip irrigation(DI),and micro-moistening irrigation(MI),and four fertilizer levels:0,93.2,186.4 and 279.6 kg/hm2(denoted as F0,F1,F2,and F3).The root zone soils of young mango trees were sampled at 30 days after each fertilization(i.e.3 days after each irrigation)for the determination of nutrient content(NO3−-N,available P and K),enzyme activity(catalase,urease and phosphatase),and microbial quantity(bacteria,fungi and actinomyces).The mongo tree growth and water-fertilizer use efficiency were investigated.The comprehensive root zone soil fertility index(SQI)and the tree growth quality index(GQI)were evaluated using the membership function with factor analysis.【Results】Micro-irrigation method and fertilization level had significant effects on soil nutrient contents,enzyme activities,microbial population,the increase range of morphological growth indices of both plant shoots and roots,and water and fertilizer use efficiency of young mango trees(P<0.05).Under the same fertilization level,soil nutrient contents were similar among the three irrigation methods,while the enzyme activities and microbial populations were in order of MI>DI>SI.Compared with SI,DI and MI increased soil enzyme activity by 15.09%−26.57%and 26.56%−48.86%,microbial quantity by 11.46%−30.19%and 12.87%−42.45%,irrigation water-use efficiency(IWUE)by 43.27%and 73.17%,partial factor productivity of fertilizer(PFP)by 33.96%and 54.44%(P<0.05).MI exhibited the highest increase in plant height and root volume,which were 100.29%and 54.06%higher than SI did.With the increase of fertilizer application levels,soil catalase activity,urease activity,microbial population,and IWUE reached peak at F2,soil nutrient content and phosphatase activity kept increasing with fertilization rate,and the PFP decreased with fertilization rate on the contrary.The correlation analysis showed that all the soil nutrient content,enzyme activity,and microbial population were positively correlated with mango growth indicators,and the degree of correlation raised in order of soil nutrient content,enzyme activity,and microbial population.Both the comprehensive SQI and GQI reached maximum at MIF2.【Conclusions】Micro-moistening irrigation coupled with 186.4 kg/hm2 of fertilizer(MIF2)is the most effective combination for promoting mango growth and improving soil environmental quality.