Soil properties under young Chinese fir-based agroforestry system in mid-subtropical China

Abstract

In order to decrease the soil nutrient loss in young planted Chinese fir (Cunningharnia lanceolata (Lamb.) Hook.) forestland and to investigate the impact of young Chinese fir plantation intercropped with crops on soil quality, a field experiment was set up in the mid-subtropics of China in 1998. The effects of growing crops in combination with young Chinese fir on soil properties were evaluated by measuring physico-chemical, microbiological and biochemical parameters five years after the beginning of this experiment. Three treatments were selected in the experiment, i.e., Chinese fir plantation intercropped with peanut (Arachis hypogaea L.) -wheat (Triticum aestivum L.) cropping sequence (C-P/W); Chinese fir plantation intercropped with maize (Zea mays L.)-wheat cropping sequence (C-M/W) and only Chinese fir plantation (Control). Soils were sampled at the 0–10 cm depth in 2003. The increases in soil nutrients (especially with respect to soil available nutrients), soil microbial biomass C (SMBC), microbial quotient (MQ), soil basal respiration (SBR), microbe numbers and enzyme activities and slight decrease in metabolic quotient (qCO2) as well as melioration in soil structure and humus quality were observed in tree-crop combinations compared with sole plantation of Chinese fir, although the differences were not always statistically significant. In addition, the evidence obtained from this study also suggests that Chinese fir-crop combination can promote the growth of young Chinese fir. Therefore, growing crops in combination with young Chinese fir can be considered a good forest management practice, helping to limit the gradual depletion of soil nutrients and, at the same time, to some degree controlling the degradation of planted Chinese fir forestland.