氮磷肥对3种牧草的生长效应和氮磷吸收的影响

采用田间试验,单因素随机区组排列,以豆科牧草柱花草和禾本科牧草扭黄茅和孔颖草为试验材料,研究适量氮磷肥的施用对3种牧草旺盛期生长及土壤氮磷吸收的影响和效果。试验结果表明,与未施氮磷肥比较,氮磷的施用有利柱花草、扭黄茅和孔颖草旺盛期(7-9月)的生长,3种牧草物候期有所延迟,可以提高3种牧草旺盛期绝对生长量,显著增加了孔颖草总生物量和氮吸收量(P<0.05)。与未施氮肥对比,施氮(施纯氮120 kg·hm^-2)有利柱花草和孔颖草对氮的吸收,显著提高柱花草含氮量和孔颖草氮的吸收量(P<0.05),促进柱花草和孔颖草的生长,提高柱花草和孔颖草地上部和地下部生物量,提高扭黄茅地上部的生长量和生物量。与未施磷肥对比,施磷(施纯磷75 kg·hm^-2)显著提高孔颖草氮的吸收量(P<0.05)。本研究为3种牧草和其他牧草氮磷的施用提供理论依据,即:适量的氮磷施用有利3种牧草产量的提高。

Herbage accumulation,and nitrogen and phosphorus absorption responses of three forage species following addition of nitrogen and phosphorus fertilizer

Herbage drymatter accumulation, and nitrogen and phosphorus absorption responses of three forage species following addition of nitrogen as urea (N) or phosphorus as superphosphate (P) fertilizer were studied over 2 seasons (2015 and 2016), in a field experiment with a randomized block design. The leguminous forage, Stylosanthes guianensis cv. Seabrana, and the forage grasses black spear grass (Heteropogon contortus) and ‘kong ying' grass (Bothriochloa pertusa) were compared with nil-fertilizer and N or P fertilizer treatments. In general, fertilizer application (especially N) delayed crop phenological development by 5-10 days. Averaged over the two growing seasons, addition of either N or P fertilizer increased forage yield by approximately 11%, but data were variable, and the yield, except B. pertusa responses to N and P were not statistically significant. Crop N and P yields (kg·ha^-1) of S. guianensis were almost double those of the two grasses tested, but only in the case of N addition to B. pertusa, was there a significant fertilizer-induced increase in forage N or P yield. Root mass of H. contortus was reduced by N or P fertilizer (P<0.05), especially by N addition. This study has provided a theoretical basis for planning the application of nitrogen and phosphorus in sub-tropical forage production. In this article, proper application of nitrogen and phosphorus is beneficial to increase the yield of the three herbages.