Ecological Function Of Cassava-Peanut Intercropping In Small Red Soil Watershed

A field experimental was conducted to investigate the effect of cassava-peanut intercropping on the stability of ecosystem functioning, and also integrating other analyses to study the response of intercropping system to photosynthesis, soil, water and so on. We discussed the internal stability of cassava-peanut intercropping from multiple perspectives. Our results showed that:(1) The diurnal variation of photosynthesis of both cassava and peanut had a single peak:the curves of photosynthetic active radiation (PAR) and atmospheric relative humidity (RH) open downward when the curves of field CO2 concentration (Ca) and atmospheric temperature (Ta) open to an opposite direction.(1) Impacted by the solar eclipse, the diurnal variation of atmospheric temperature (Ta), photosynthetic active radiation (PAR) and field CO2 concentration (Ca) were all significantly reduced, while atmospheric relative humidity (RH) was increased.When total solar eclipse occurred, peanuts under intercropping showed a higher resistance to the disturbance than single system, reflecting the advantage of intercropping. Following the total solar eclipse, the restoration of net photosynthetic efficiency (Pn) of peanut under single system became greater, reflecting the single advantage. With the model based on leaf temperature, we created a model named intercropping dominance (ID). The ID of cassava-peanut intercropping derived+0.83% which verified that cassava-peanut intercropping had indeed advantages under normal weather conditions.(2) Among the several intercropping systems, narrow-intercropping had no apparent advantage while wide-intercropping seems to be an optimal one. However, the WUE and Ls of wide-intercropping were the lowest which would make it not appropriate in the drought prone region; Double-intercropping had a high efficient use of water and CO2 which would play an important role in the area subjected to periodical shortage of water. Analysis of variance showed that the soil physico-chemical properties in the line of 1.3.5 from cassava had no significant difference(p> 0.05). That means that soil properties under intercropping practices not influenced by distance.(3) Under different depth of soil, the number of nematodes from intercropping system was higher than that from the single one, but the difference did not reach significant level. Intercropping measures reduced the MBN level of the surface soil (0-15 cm) and deep soil (30-45 cm) but significantly increased MBC, MBN content (p<0.05) of the middle soil (15-30 cm).(4) Compared to monoculture, intercropping models can significantly lower content of nitrogen and available phosphorus (p<0.05), while the potassium content is relatively stable. The intercropping models significantly reduced the soil organic matter content in the surface and middle soil (p<0.05), while organic matter in the deep soil (30-45cm) was not affected.(5)While promoting the performance of water retention undoubtedly, cassava-peanut intercropping also exacerbated the red soil acidification.