Long‐term nitrogen balance for pearl millet (Pennisetum glaucum L.) in an acid sandy soil of Niger
Long‐term nitrogen balance for pearl millet (Pennisetum glaucum L.) in an acid sandy soil of Niger
复制标题
尼日尔酸性沙土中珍珠粟（Pennisetum glaucum L.）的长期氮平衡
DOI：
10.1002/jpln.19931560212
复制
发表时间：
1993
影响因子：
2.5
通讯作者：
H. Marschner
中科院分区：
文献类型：
--
作者：
H. Hafner;J. Bley;A. Bationo;P. Martin;H. Marschner
在尼日尔（西非）的酸性沙质土壤上，在降雨量正常或高于平均水平的年份，珍珠粟 (Pennisetum glaucum L.) 的氮肥回收率通常超过 100%。固氮细菌的生物固氮（BNF）可能有助于珍珠粟种植系统的氮供应。对于一项长期田间试验，包括使用和不使用矿物肥料 (F) 以及使用和不使用农作物残留物 (CR) 的处理，计算了六年期间（1983-1988）的氮平衡表。
连续种植小米六年后，总氮吸收量（36-77 kg N ha−1 yr−1）明显高于施氮量（30 kg N ha−1 yr−1）。雨水中NH4-N和NO3-N的大气输入量约为2 kg N ha−1 yr−1，其中70%以NH4-N的形式存在。根据其他实验估计，尿素（播撒、掺入）中的气态 NH3 损失达到所施用肥料氮的 36%。淋滤造成的氮损失（15 至 > 25 kg N ha−1 yr−1）取决于处理以及单次降雨事件（> 50 mm）的数量和分布。土壤总氮含量（0-60 cm）的下降范围为 15 至 48 kg N ha−1 yr−1。长期氮平衡（1983-1988）表明年净增量在 6 (+CR-F) 和 13 (+CR+F) kg N ha−1 yr−1 之间。对于对照（-CR-F），长期氮平衡为负（10 kg N ha−1 yr−1）。在仅使用农作物残留物的处理中，氮平衡主要由淋失损失决定，而在施用矿肥的处理中，氮平衡主要取决于谷子作物的氮去除。氮平衡的年净增量从使用矿物肥料的 7 kg ha−1 增加到使用矿物肥料加作物残茬的组合的 13 kg ha−1。
在根际和大块土壤（0-15 厘米）中，总细菌种群的 9% 至 45% 是固氮（固氮）细菌。施用作物残茬后氮增益的增加与固氮菌和总细菌数量的增加呈正相关。细菌数量的数据表明，长期氮平衡中氮的增加很可能是由于生物固氮的氮输入所致。此外，相关研究表明，施用作物残茬导致根际固氮菌和总细菌增殖，刺激了珍珠粟根系生长，从而改善了缺磷土壤对磷（P）的吸收。
On acid sandy soils of Niger (West Africa) fertilizer N recovery by pearl millet (Pennisetum glaucum L.) is often more than 100 per cent in years with normal or above average rainfall. Biological nitrogen fixation (BNF) by N2-fixing bacteria may contribute to the N supply in pearl millet cropping systems. For a long-term field experiment comprising treatments with and without mineral fertilizer (F) and with and without crop residue application (CR) a N balance sheet was calculated over a period of six years (1983-1988).
After six years of successive millet cropping total N uptake (36-77 kg N ha−1 yr−1) was distinctly higher than the amount of fertilizer N applied (30 kg N ha−1 yr−1). The atmospheric input of NH4-N and NO3-N in the rainwater was about 2 kg N ha−1 yr−1, 70 % in the form of NH4-N. Gaseous NH3 losses from urea (broadcast, incorporated) were estimated from other experiments to amount to 36 % of the fertilizer N applied. Nitrogen losses by leaching (15 to > 25 kg N ha−1 yr−1) were dependent on the treatment and on the quantity and distribution of single rainfall events (>50 mm). Decline in total soil N content (0-60 cm) ranged from 15 to 48 kg N ha−1 yr−1. The long-term N balance (1983-1988) indicated an annual net gain between 6 (+CR-F) and 13 (+CR+F) kg N ha−1 yr−1. For the control (-CR-F) the long-term N balance was negative (10 kg N ha−1 yr−1). In the treatment with crop residues only, the N balance was mainly determined by leaching losses, whereas in treatments with mineral fertilizer application the N balance depended primarily on N removal by the millet crop. The annual net gain in the N balance increased from 7 kg ha−1 with mineral fertilizer to 13 kg ha−1 in the combination mineral fertilizer plus crop residues.
In both the rhizosphere and the bulk soil (0-15 cm), between 9 and 45% of the total bacterial population were N2-fixing (diazotrophic) bacteria. The increased N gain upon crop residue application was positively correlated with an increase in the number of diazotrophic and total bacteria. The data on bacterial numbers suggest that the gain of N in the longterm N balance is most likely due to an N input by biological nitrogen fixation. In addition, evidence exists from related studies that the proliferation of diazotrophs and total bacteria in the rhizosphere due to crop residue application stimulated root growth of pearl millet, and thus improved the phosphorus (P) acquisition in the P deficient soil.