枣粮间作养分利用与表观损失空间差异性

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间作作物产量、氮磷营养元素利用与表观损失方面的空间差异性,并对枣粮间作、枣树单作和农田3种生态系统进行了比较.结果表明:(1)枣粮间作系统内间作作物产量随着距枣树种植行距离的缩小而迅速降低,表现出明显的空间差异性.虽然与农田生态系统比较,间作小麦、玉米均表现减产,经济产量分别降低11.4%、39.9%,但整个枣粮间作系统提高了土地利用程度;(2)枣粮间作系统间作作物吸收氮磷量也呈现明显空间差异性,且与间作作物生物量有极显著相关性.3种生态系统相比,吸氮量为枣粮间作>枣树单作>农田;吸磷量为农田>枣粮间作>枣树单作;(3)枣粮间作系统内氮磷表观损失量有明显的空间差异性,距枣树种植行0.25m处表观损失量显著高于其它位置表观损失量,在距枣树种植行6.5m到2m范围内,随着与枣树种植行的接近,氮磷表观损失量有所降低.3种生态系统相比,氮、磷表观损失量均为枣树单作>农田>枣粮间作.

Horizontal variation of nutrient uptake and apparent loss in jujube/crop intercropping ecosystem

The jujube/crop intercropping ecosystem (JIE) is an important pattern of agro-forestry and distributed widely in North China. The researches are still lacking in the spatial variation of crop yield, nitrogen (N) and phosphorus (P) uptake and apparent loss within JIE. In order to understand the spatial heterogeneity of the intercropping ecosystem, the experiment were carried out at village Dashujin, Nanpi County, Hebei Province during 2005-2006. The soil and plant samples were collected from different site in JIE, i.e. 0.25, 1, 2, 3, 4.5 m and 6.5 m away from the jujube row. And these parameters of the JIE were also compared with the ones in jujube mono-cropping ecosystem (JME) and farmland ecosystem (FE). The results showed that there was an evident horizontal variation of crop yield in JIE. The crop yield decreased obviously closing to jujube row. Compared with FE, there was an 11.4% and 39.9% decrease, respectively, in the grain yield of wheat and maize in JIE. However, the whole JIE increased the land using efficiency. The horizontal variation of N and P uptake was apparent in JIE. And there was a significant positive relationship between crop dry matter production with N and P uptake (P<0.01) in JIE. The order of the quantity of N uptake was JIE>JME>FE and for P it was in the order of FE>JIE>JME. The results also showed that in JIE the N and P apparent loss varied with the distance from the row of jujube trees. The highest value of N and P apparent loss was located at 0.25m away from the jujube. From 6.5m to 2m away from the jujube, N and P apparent loss decreased mildly. The order of the quantity of N and P apparent loss was JME>FE>JIE. JIE increased land using efficiency and decreased N and P apparent loss in the study area. But it was an ecosystem with great spatial heterogeneity, which required adjusting the field management to the different area in JIE.