秸秆和生草覆盖对桃园土壤养分含量、微生物数量及土壤酶活性的影响

 以秸秆(覆盖重量分别为小麦(Triticum aestivum)秸3.25 kg·m^–2、玉米(Zea mays)秸1.97 kg·m^–2、禾本科杂草3.67 kg·m^–2)和生草(白三叶草(Trifolium repens)、高羊茅(Festuca arundincea)和紫花苜蓿(Medicago sativa), 播种量均为50 kg·hm^–2)为覆盖材料, 以不覆盖为对照, 研究了不同覆盖材料对桃园土壤微生物数量和酶活性的影响, 及其与土壤养分的关系。结果表明, 与对照相比, 除覆盖生草根际和非根际土壤全磷和速效磷含量差异均不显著外, 其他处理根际和非根际土壤碱解氮、速效钾、全氮、全钾和有机质含量差异均达到显著水平; 所有处理根际和非根际土壤氨化细菌、真菌和放线菌数量、土壤含水率和pH值、土壤脲酶和磷酸酶活性差异均达到显著水平。白三叶草处理的根际和非根际土壤碱解氮、速效钾、全氮、全钾、有机质含量, 土壤氨化细菌和真菌数量, 土壤脲酶和磷酸酶活性的平均升幅均最高, 分别为99%、270%、267%、117%、272%、158%、141%、156%和64%。氨化细菌、真菌、放线菌、脲酶和磷酸酶分别与土壤碱解氮、速效钾(放线菌和磷酸酶除外)、全氮、全钾和有机质呈显著或极显著的正相关。通径分析表明, 在3种土壤微生物和2种酶对养分含量的影响中, 脲酶是影响土壤碱解氮、速效钾、全氮、全钾和有机质的主要因子。

Effects of straw and living grass mulching on soil nutrients, soil microbial quantities and soil enzyme activities in a peach orchard

Aims My aims were to (a) study the effects of mulching materials on microbial quantities, enzyme activities and soil nutrient contents and their relationships and (b) explore feasibility of using soil microbial quantities and soil enzyme activities as indicators of soil health.
Methods Straw of wheat (Triticum aestivum), stalks of corn (Zea mays) and weeds with 3.25, 1.97 and 3.67 kg·m^–2 of covering weight, respectively, and living grass (Trifolium repens, Medicago sativa and Festuca arundinacea) with 50 kg·hm^–2 of sowings were used as mulching materials, with no covering as the control.
Important findings The contents of alkali-hydrolyzable nitrogen (N), available potassium (K), total N, total K and organic matter of the rhizospheric and non-rhizospheric soils were significantly increased by straw and living grass mulching, except for total phosphorus (P) and available P in the living grass treatment. Quantities of ammonification bacteria, fungi and actinomycetes, as well as soil moisture, pH value and activities of urease and phosphatase significantly increased in all treatments. Greatest mean increases of alkali-hydrolyzable N (99%), available K (270%), total N (267%), total K (117%), organic matter (272%), quantities of ammonification bacteria (158%) and fungi (141%) and activities of urease (156%) and phosphatase (64%) occurred in the Trifolium repens treatment. Soil alkali-hydrolyzable N, available K, total N, total K and organic matter showed significantly positive correlation with the amount of ammonification bacteria, fungi and actinomycetes and activities of urease and alkaline phosphatase, except for soil available K with actinomycetes and phosphatase. Path analysis indicated that soil urease activity was the most important factor affecting the accumulation of alkali-hydrolyzable N, available K, total N, total K and organic matter in the three types of soil microbes and two kinds of enzymes.