YIELD, PERCENT NITROGEN, AND TOTAL NITROGEN UPTAKE OF VARIOUS CALIFORNIA ANNUAL GRASSLAND SPECIES FERTILIZED WITH INCREASING RATES OF NITROGEN
YIELD, PERCENT NITROGEN, AND TOTAL NITROGEN UPTAKE OF VARIOUS CALIFORNIA ANNUAL GRASSLAND SPECIES FERTILIZED WITH INCREASING RATES OF NITROGEN
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DOI：
10.2134/agronj1963.00021962005500030014x
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发表时间：
1963-01-01
期刊：
影响因子：
2.1
通讯作者：
JONES, MB
中科院分区：
文献类型：
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作者：
JONES, MB
在加利福尼亚州2种土壤类型的一年生草地上，以每英亩160磅的增氮率施氮。产量，氮浓度和氮吸收测定个别物种在生长季节的四个日期。在加州北部沿海的草地地区，施氮的主要好处是在冬季牧草生长缓慢，牧草产量增加。每英亩施氮量不应超过80磅，因为增加大量的氮素对冬季产量的增加很少。超过每英亩80磅的产量增加出现在春季，主要取决于温暖的春季月份的降雨量和分布。第二年有一些N残留，但只有在160磅的速度下才能测量。所有的N率增加的N浓度的植物在本赛季初。随着植物成熟，以较低的速率施用的N被用于额外的生长，以至于非豆科物种中的N百分比通常随着每英亩增加40磅N而降低。每英亩施80磅氮的植物，其氮浓度一般与未施氮的植物相当;每英亩施160磅氮一般会增加非豆科植物的氮含量。施氮的效果反映在随着施氮量的增加，草和丝草对氮的吸收增加，而三叶草对氮的吸收减少。三叶草在3月至4月期间的总氮量增幅最大，而在4月期间没有施氮。每增加一个N减少豆科牧草的N的贡献。
Increasing rates of N up to 160 pounds per acre were applied to California''s annual grassland on 2 soil types. Yields, N concentrations and N uptake were determined for individual species at four dates during the growing season. The primary benefit of N fertilization in the grassland areas of north coastal California was the increase in production of forage during the winter season when grass was short and legumes grew very slowly. Not more than 80 pounds N per acre should be applied s ince very little increase in winter production resulted from the addition of greater amounts of N. An increase inyield above the 80-pounds-per-acre rate came in the spring and was dependent primarily upon the amount and distribution of rainfall during the warm spring months. There was some carryover of N into the second year, but it was measurable only at the 160-pound rate. All rates of N increased the N concentration in the plants early in the season. As the plants matured, N applied at the lower rates was utilized in additional growth to the extent that the percent N in the nonleguminous species was usually decreased with the addition of 40 pounds N per acre. Plants fertilized with 80 pounds N per acre generally had concentrations of N equivalent to that of unfertilized plants; 160 pounds N per acre generally increased the percent N of the nonleguminous plants. The effect of the applied N was reflected in the increased uptake of N by the grasses and filaree and decreased N uptake by clover with each additional increment of nitrogen applied. The clovers made their largest gains in total N from March to April where no N was applied. Each increment of N reduced the legume contribution of N to the forage.