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在加利福尼亚西北部,水分通常不是冬春草地生产的限制因素。因而,弄清其它生境因素(物理、化学因素)如何影响草地生产是很重要的。运用Ridge回归分析和单相关评价草地生产与草场坡度、海拔、土层厚度、土壤质地及其容重,持水量、pH和肥力(包括有效磷、硫、交换性阳离子、全氮、全硫和有机质)的关系。对17个典型草场的4种施肥处理(P_0S_0,P_300S_0,P_0S_90,P_300S_90)进行地三叶—禾草产量测定。不施肥时,土壤pH和有效磷看来是与产草量关系最密切的两个变量。施磷和硫时,产草量增加。单施磷时,土壤交换性钾与产草量关系最密切;而单施硫时,有效磷与产草量关系最密切。当磷、硫配合施用时,土壤有效磷和有效钾与产草量密切相关。一般说来,施硫对牧草产量有显著的效应,然而本试验表明,土壤有效硫却与产草量相关性不强。
In the northwestern California, moisture is not usually a limiting factor in winter or spring grass production. Therefore, it is important to understand how other habitat factors (physical and chemical) affect grassland production. Ridge regression analysis and single-correlation analysis were used to evaluate grassland productivity and pasture slope, elevation, soil thickness, soil texture and bulk density, water holding capacity, pH and fertility (including available phosphorus, sulfur, exchangeable cations, total nitrogen, total sulfur and organic matter )Relationship. Four kinds of fertilization treatments (P_0S_0, P_300S_0, P_0S_90, P_300S_90) of 17 typical pastures were conducted to determine the production of trefoilgrass. Soil pH and available phosphorus appear to be the two variables most closely related to yield when no fertilizer is applied. Phosphorus and sulfur, the production increased. When phosphorus was applied, the exchangeable potassium was the most closely related to the yield of grassland. When applying sulfur alone, the relationship between available phosphorus and grass yield was the most closely related. When phosphorus and sulfur were applied in combination, available phosphorus and available potassium were closely related to grass yield. In general, the application of sulfur has a significant effect on pasture production, however, this experiment shows that there is no correlation between available sulfur and grass yield.