Effects of Organic Material Application Patterns on the Enhancement of Organic Carbon and Crop Yield in Grey Desert Soil

Objective The aim was to explain the effects of organic material addition on soil organic carbon (SOC) and crop yield.

Methods This study was carried out in long-term locational fertilization experiment station on grey desert soil started in 1990. Seven typical fertilization treatments (no fertilization, CK; MacroNPK, NPK; MacroNPK + Macroorganic fertilizer, NPKM; incremental NPK + incremental organic fertilizer, 1.5NPKM; MacroNPK + straw returning, NPKS; straw returning, S; single application of organic fertilizer, M) were used to study SOC content changes, the relationship between various carbon inputs and SOC content, and the correlation between SOC content and crop yield. It also examined the effects of various fertilizers on the physicochemical properties of soil.

Results ① Under long-term fertilization, SOC contents under NPKM, 1.5NPKM and M treatments were significantly positively correlated with the years of fertilization, and increased by 15.65, 29.45 and 27.34 g kg⁻¹ compared with CK treatment after 33 years, respectively. ② Compared with no fertilization treatment, fertilization could increase the carbon input of the field root by 1.10 ~ 1.61 t hm⁻². There was a significant linear correlation between SOC content and total organic carbon input. ③ In 0 ~ 20, 20 ~ 40 cm soil layer, the addition of organic fertilizer (NPKM, 1.5NPKM, M) significantly increased the soil available nutrient content compared with NPK treatment. ④ The increase of SOC content promoted the increase of crop yield. The wheat, maize, and cotton yields increased by 132.25, 105.48, and 61.02 kg hm⁻², respectively, when the SOC content every increased by 1.00 g kg⁻¹. The stability of SOC on crop yield increase in NPK treatment was superior to those in NPKM and 1.5NPKM treatments. ⑤ Correlation analysis showed that soil available phosphorus, available potassium and alkali-hydrolyzed nitrogen were positively correlated with SOC content and crop yield, while pH was negatively correlated with SOC content.

Conclusion The addition of exogenous organic materials not only increased SOC content, but also was conducive to the sequestration of organic carbon and the content of soil available nutrients, and finally improved crop yield. The addition of organic fertilizer can reduce soil pH, and the combination of organic and inorganic fertilizer is the best method of fertilization.