DINITROGEN FIXATION, AND N AND DRY-MATTER DISTRIBUTION DURING 4 YEAR STANDS OF BIRDSFOOT-TREFOIL AND RED-CLOVER
DINITROGEN FIXATION, AND N AND DRY-MATTER DISTRIBUTION DURING 4 YEAR STANDS OF BIRDSFOOT-TREFOIL AND RED-CLOVER
复制标题
DOI：
10.2135/cropsci1985.0011183x002500010026x
复制
发表时间：
1985-01-01
期刊：
影响因子：
2.3
通讯作者：
HENJUM, KI
中科院分区：
文献类型：
--
作者：
HEICHEL, GH;VANCE, CP;HENJUM, KI
鸟脚三叶草和红三叶草是重要的多年生豆科牧草，在轮作中用作干草或牧草。尽管它们传统上被用作种植系统的氮源，但关于鸟脚三叶草和红三叶草在长期林分中固定的氮气量的信息很少。用15N同位素稀释法在4年林分内进行了田间试验，以确定用于生产干草的鸟脚金、三叶草和红三叶草对氮素的年际和年内固定以及干物质在各器官之间的分配。不同豆科牧草在一年内和不同林分年间对氮素的固持差异显著。在林分的前3年，红三叶草的年平均牧草干物质产量比鸟脚三叶草高22%。尽管如此，这2个种。根和冠的干物质含量相似，氮气的年平均含量固定在大约60至120千克N/公顷之间。在第4年，鸟脚三叶草对氮素的固定比红三叶高出42%，这是因为它从类似草本植物的固定和根干物质生产中获得了显着更大的总氮比例。在4年生林分寿命中，两个树种在氮气固定下每年平均为92公斤氮/小时。在整个试验过程中，鸟脚三叶草和红三叶草将其干物质的10%或更少分配给根和树冠，这些成分的氮浓度通常是牧草的0.5-0.6。固定氮素对后茬作物的最大回报将来自于采用管理做法，实现牧草的大幅增长，而不仅仅是在干草收获后不久的根和冠。
Birdsfoot trefoil and red clover are important perennial forage legumes for use as hay or pasture in crop rotations. Despite their traditional usage as a source of N for cropping systems, little information is available on the amounts of N2 that birdsfoot trefoil and red clover fix during long-term stands. Field experiments were conducted with the 15N isotope dilution method over a stand life of 4 yr to determine the inter- and intra-annual fixation of N2 and the distribution of dry matter among organs for birdsfoot trefoil and red clover managed for hay production. Each legume species showed significant variation of N2 fixation within a year and among years of the stand. Red clover annually produced 22% greater average herbage dry matter compared with birsfoot trefoil during the first 3 yr of the stand. Nevertheless, the 2 spp. had similar quantities of dry matter in roots plus crowns and fixed similar average annual quantities of N2 ranging from about 60 to 120 kg N/ha. Dinitrogen fixation of birdsfoot trefoil exceeded that of red clover by 42% in Year 4 because it obtained a significantly greater proportion of its total N from fixation with similar herbage and root dry matter production. Over the 4-yr stand life, both species averaged 92 kg N/h annually from N2 fixation. Throughout the experiments, birdsfoot trefoil and red clover distributed 10% or less of their dry mtter to roots plus crown, components which usually had a N concentration 0.5 to 0.6 that of herbage. The greatest return of fixed N2 to a subsequent crop would result from adoption of management practices that achieve a plowdown of a substantial growth of herbage rather than only roots plus crowns soon after hay harvest.