Objectives Acidification is one of the prominent problems leading to degeneration of soil quality. We studied the pH thresholds of main crop production and the influence factors, to provide theoretical basis for soil acidification control.
Methods Taking maize, rice, wheat, soybean, soil pH and crop yield as the key words, literatures published from 1980 to 2020 were searched in Database of CNKI and Web of Science. Based on field experiments at home and abroad, the relationship between the yield of corn, rice, wheat and soybean and soil pH was analyzed. Sigmoid function was used to calculate the crop acid damage threshold, and Pearson correlation analysis and partial correlation analysis were combined to identify the main influencing factors of crop acid damage threshold.
Results 1) The yield of four crops showed an “S” shape with the decrease of soil pH. The acid damage thresholds of 95% yield of maize, soybean, wheat and rice were 5.87, 5.34, 5.32 and 4.21, respectively. 2) Crop yield was negatively correlated with soil pH, exchangeable acid, exchangeable Al (P<0.05), and positively correlated with exchangeable Ca, Ca-Al ratio, organic matter, available P, N application amount (P<0.05). When soil pH was higher than the acid damage threshold, crop yield was positively correlated with organic matter and available P (P<0.05); when soil pH was lower than the acid damage threshold, crop yield was positively correlated with soil pH, exchangeable Ca and Ca-Al ratio, and negatively correlated with exchangeable Al (P<0.05). 3) Partial correlation analysis showed that removing the influence of organic matter increased the correlation coefficient (r) of relative yield with pH by 0.207, increased the r of exchangeable Al with relative yield by 0.072; removing the influence of available P increased the r of relative yield with pH by 0.085, and increased the r of exchangeable Al with relative yield by 0.147; removing the influence of N application rate increased the r of relative yield with pH by 0.026, and the r of exchangeable Al with relative yield by 0.009. Available P, organic matter and chemical N application rate are the key factors affecting the response of crop yield to soil pH.
Conclusions When soil pH is lower than the acid damage threshold, the content of available P and organic matter affect the response of crop yield to soil pH, the higher the available P and organic matter, the less the acid damage to crop yield.
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