间作与施氮对牧草生物量、种间竞争和氮磷吸收的影响

本研究采用双因素随机区组田间试验，研究了间作与施氮对柱花草（Stylosanthes guianensis）和扭黄茅（Heteropogon contortus）生物量、土壤氮磷吸收能力及柱花草/扭黄茅间作体系的土地当量比、种间相对竟争能力和相对拥剂系数的影响。结果表明，相同氮水平下，与柱花草单作比较，间作降低了柱花草对土壤氮磷的吸收，未施氮（N0）处理下氮磷的吸收量分别减少15.95%和12.86%，施氮（N120 kg·hm^-2）处理下氮磷的吸收量分别减少41.98%和51.14%，抑制柱花草的生长，地上部生物量分别减幅9.69%（N0）和39.43%（N120），地下部生物量分别减幅9.01%（N0）和53.21%（N120）。但间作提高了扭黄茅对土壤氮磷的吸收量，N0水平下氮磷的吸收量分别增加4.09%和10.62%，N120水平下氮磷的吸收量分别增加31.86%和39.78%，促进扭黄茅地上部的生长，N0和N120水平地上部生物量分别提高4.43%和24.98%。N0水平间作模式当量比均大于1，具有间作优势。相对柱花草，与扭黄茅间作的相对拥挤系数小于1，种间竞争能力小于0，为豆禾牧草的优化配置提供理论依据。

Effects of Intercropping of Leguminous and Gramineaes and Nitrogen Fertilizer Application on Biomass,Aggressivity,Nitrogen and Phosphorus Absorption of Forage Species

A two factors randomized block field experiment was carried out to study the effects of nitrogen fertilizer and intercropping of Stylosanthes guianensis and Heteropogon contortus on the biomass,nitrogen and phosphorus absorption from soil,land equivalent ratio of the intercropping system,species aggressivity and relative crowding coefficient. The results showed that:compared with monocultured S. guianensias,intercropping management reduced the absorption of nitrogen and phosphorus from the soil respectively by 15.95% and 12.86% in N-free (N0) treatments,and by 41.98% and 51.14% in nitrogen fertilized (N120 kg·hm^-2) treatments,the growth of S. guianensias were inhibited,aboveground biomass decreased by 9.69% (N0) and 39.43% (N120) and the belowground biomass decreased by 9.01% (N0) and 53.21% (N120) respectively. On the other hand,compared with monoculture,intercropping with S. guianensis increased the absorption of nitrogen and phosphorus of H. contortus from the soil respectively by 4.09% and 10.62% in N-free (N0) groups,and by 31.86% and 39.78% inN120 groups,the aboveground biomass of H. contortus were increased by 4.43% in NO groups and 24.98% in N120 groups,respectively. The intercropping equivalence ratios of N0 groups were greater than 1 and showed an intercropping advantage. Compared to S. guianensias,the relative crowding coefficient was less than 1 when intercropped with H. contortus,and the interspecies competitive ability was less than 0. The study provides a theoretical basis for the optimizing plantation of different species of forage grasses.