Effects of intercropping on nitrogen component in latosolic red soil of slope land in young orchard

Objective  To explore the effects of different intercropping patterns on nitrogen components of latosolic red soil of slope land in young orchard, and identify an optimal intercropping pattern that could improve soil nitrogen availability in orchard.

Method  A field experiment was carried out in Dimocarpus longan (Dl) orchard for two seasons (in autumn of 2015 and spring of 2016) to investigate the effects of four planting patterns Dl monoculture (CK), Dl intercropping with Arachis hypogaea (Dl/Ah), Dl intercropping with Stylosanthes guianensis (Dl/Sg) and Dl intercropping with Lolium perenne (Dl/Lp) on the contents of soil total nitrogen (TN), available nitrogen (AN), NO₃^–-N, dissolved organic nitrogen (DON) and micrbial biomass nitrogen (MBN).

Result  Soil TN contents of Dl/Ah and Dl/Sg treatments and soil MBN contents of intercropping treatments were significantly higher than that of CK at the maturing stage of A. hypogaea in two seasons. At the pegging stage of A. hypogaea in two seasons, soil DON and AN contents of Dl/Ah treatment were significantly higher than that of CK. NO₃^–-N contents of Dl/Ah and Dl/Sg treatments were significantly higher than that of CK, and enhanced by 64.4% and 34.2% respectively at the pegging stage of A. hypogaea in 2016. Soil TN, DON and NO₃^–-N contents had a significantly positive correlation with plant nitrogen content, but were negatively correlated with the carbon content and carbon/nitrogen ratio of plant.

Conclusion  Dl/Ah and Dl/Sg treatments could significantly improve soil nitrogen component contents, and Dl/Ah treatment was better.