Abstract: Northwest China is burdened by declining soil fertility and poor capacity of water and nutrient retention. A pot experiment was conducted to examine the effects of organic acid conditio-ners (OASC) with four application rates (0, 20, 40, and 60 g·kg^-1) on soil nutrients and crop growth. Maize and common vetch were the focus crops and loessial soil and irrigated desert soil were the soil types. The results showed that OASC application reduced water evaporation loss and significantly improved soil available nutrient content, with the most obvious effects on soil phosphorus. Available phosphorus content and proportion were increased by 256.5% and 227.4%, respectively, compared with no OASC treatment. The shoot dry weights of maize and common vetch on loessial soil were initially increased with the increasing OASC application rate and were highest at the application rate of 20 g·kg^-1. The values progressively decreased with increasing OASC addition rates. Total salt content was significantly increased and the rate of emergence of common vetch decreased at OASC rate exceeding 20 g·kg^-1. For irrigated desert soil, the OASC application rate did not affect total salt content when maize was planted. There was significant increase in soil total salt contents when common vetch was planted and at the OASC rate of 60 g·kg^-1. The shoot dry weight of common vetch and maize was highest with the OASC application rates at 40 g·kg^-1 and 60 g·kg^-1, respectively. The optimal OASC rate for planting common vetch and maize on loess soil was 20 g·kg^-1. The application rates of 40 g·kg^-1 and 60 g·kg^-1 were optimal for planting common vetch and maize on irrigated desert, respectively.

Key words: irrigated desert soil, loessial soil, maize, common vetch, organic acid soil conditio-ner, dry weight