饱和铵贮库施肥对玉米根系空间分布和氮素吸收的影响

采用根箱栽培研究饱和铵贮库(nitrogen depot with saturated ammonium,NDSA)施肥法对玉米根系空间分布和氮素吸收的影响.结果表明:饱和铵贮库施肥显著促进了玉米根系及地上部的生长,其根和地上部鲜质量分别增加了18%和37%;饱和铵贮库施肥法能使玉米根系围绕施肥点形成根球",其根系主要集中在离施肥中心点6~8 cm的土体中;饱和铵贮库施肥的玉米根、茎、叶的氮吸收量分别比常规施肥高43%、30%、31%,氮肥表观利用率提高了15%;饱和铵贮库施肥处理离施肥中心点6~8 cm土体中的铵态氮含量比常规施肥高出2倍以上,而硝态氮含量则减少1倍以上,表明饱和铵贮库施肥法可有效抑制铵态氮向硝态氮的转化.由此可见,饱和铵贮库施肥通过诱导根系生长、改变根系在土壤中的空间分布及构型,最终形成根球,并对铵的硝化进行有效抑制是其减少土壤氮素损失,大幅提高植物氮素利用率,促进植株生长的一个重要机制.

Effect of nitrogen depot with saturated ammonium (NDSA) fertilization on the spacial distribution of corn root and N uptake .

Rhizobox experiments were carried out to study the effect of nitrogen depot with saturated ammonium (NDSA) fertilization on the spacial distribution of corn roots and N uptake . The results indicated that the growth of the roots and shoots of corn were significantly promoted by NDSA fertilization . The fresh mass of roots and shoots was increased by18% and37% respectively compared with that of the conventional fertilization . The corn roots distributed mainly in the soil layer away from the center of NDSA6 to8 cm and formed a root ball around the fertilized spot in NDSA treatment . N uptake of corn roots,stems and leaves was increased by43%,30%,31%,respectively,and apparent N utilization was increased by15% in NDSA treatment compared with that of the conventional fertilization treatment . The ammonium content of NDSA treatment was more than two times higher than that of conventional fertilization,while the nitrate decreased to a half,indicating that the NDSA inhibited the transformation of ammonium to nitrate . Therefore,it can be concluded that under NDSA fertilization,a root ball" formed by inducing root growth,altering its spacial distribution and architecture in the soil and inhibition to nitrification may refers to one of most important mechanisms for NDSA fertilization reducing nitrogen loss,increasing N utilization rate and promoting plant growth .