基于枣粮间作复合生态系统内部异质性,通过在系统内不同位置采样,分析了枣粮间作系统内土壤氮素水平分布特性.结果表明:①枣粮间作生态系统中,在小麦收获期和玉米收获期两个时期,土壤全氮和硝态氮含量均存在明显的水平变异性.土壤全氮含量在距枣行1～6. m范围内,随着与枣行距离的缩短,呈先增加后降低的变化趋势,最高值出现在距枣行3 m处.土壤硝态氮含量随着与枣行距离的缩短而迅速增加.而土壤铵态氮含量极低且没有明显的水平变异;②氮素施用量对土壤全氮和硝态氮空间变异有正向作用,而植株对氮的吸收利用可以降低土壤氮素分布空间差异程度.各因子对土壤全氮空间变异影响强弱顺序为氮吸收量＞氮素施用量＞土壤含水量;对土壤硝态氮空间变异影响强弱顺序为氮素施用量＞土壤全氮含量＞氮素吸收量＞土壤含水量.
关键词：
枣粮间作; 土壤; 全氮; 硝态氮; 分布
In order to understand the horizontal heterogeneity of soil nitrogen in the jujube2crop intercropping ecosys2 tem(J IE),the experiment was carried out at village Dashujin,Nanpi County,Hebei Province during 2005 - 2006. The soil samples were collected from different site in J IE,i1e10125,2,3,415 and 615 m away from the jujube row to determine the horizontal distribution characteristics of soil total nitrogen (TN),nitrate nitrogen (NO3 - 2N) and ammonium nitrogen (NH4 +2N). The results showed that the horizontal variances of soil TN and NO3 - 2N distribution were obvious at harvest stages of wheat and maize in J IE,but the distribution of soil NH4 +2N had no obvious horizontal variance.When the dis2 tance to the jujube tree row(JTR) decreased from 6. 5 m to 1 m,the soil TN concentration increased first and then de2 creased,and the highest soil TN concentration came from the 3 m sampling site. However,the NO3 - 2N concentration in2 creased rapidly along with the shortened distance to JTR. The results also showed that fertilizer application rate had a great positive effect on the horizontal variances of soil TN and NO3 - 2N,whereas N uptake had a negative effect on them. The main factor affecting the spatial variance of soil TN was N uptake,followed by N application rate and soil water content, while the order of affecting the spatial variance of soil NO3 - 2N was N application rate > soil TN concentration > N uptake > soil water content.
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