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The critical pH was the target pH for soil acidity improvement, which has important guiding significance for agricultural production and sustainable development. A pot experiment was conducted to investigate the effect of soil initial properties affecting the response of wheat growth to pH. 5 soils derived from plate shale, quaternary red earth, river alluvium, tertiary red sandstone, and granite were used in this study. The results showed that the maximum shoot biomasses of wheat were 2.71, 1.17, 2.06, 1.57 and 1.70 g⋅pot-1 for soils derived from plate shale, quaternary red earth, river alluvium, granite, and tertiary red sandstone, respectively. The critical values of pH95%, pH50%, or pH5% were defined as shoot biomass reaching to 95%, 50%, or 5% of maximum values. The pH95%, pH50%, or pH5% were 5.31, 4.42, and 3.53 for soil derived from plate shale, 5.79, 4.79, and 3.80 for quaternary red earth, 5.25, 4.71, and 4.16 for river alluvium, 4.94, 4.61, and 4.29 for tertiary red sandstone granite, and 5.72, 4.66, and 3.59 for granite, respectively. The maximum values of shoot biomass had significant positive correlations with soil initial pH, available P, exchangeable Mg and exchangeable Ca. The pH50% of wheat shoot biomass was negatively correlated with soil initial available P; and the pH50%of wheat height was negatively correlated with soil initial available P and exchangeable Mg. The data indicated that soil initial available P and exchangeable Mg shaped the response of wheat growth to pH and the maximum values of crop biomass were determined by both soil nutrient status and acidity. Therefore, we recommend that co-amelioration of soil fertility and acidity was a practical method to reach a best condition for plant growth. [ABSTRACT FROM AUTHOR]

The easy fixation of phosphorus fertilizer in soil is a main reason for the low utilization rate of phosphorus fertilizer. In order to study the effects of fertilization frequency on availability of phosphorus fertilizer, three cinnamon soils with different Olsen-P levels (19.4, 24.2, 49.7 mg·kg-1) were collected in the long-term fertilization test based on Shouyang County, Jinzhong City Shanxi Province, and the same amount of phosphorus fertilizer (potassium dihydrogen phosphate) was added to the soil with different Olsen-P levels by once and 3 times, respectively. The soil with Olsen-P was incubated under constant temperature condition for 90 d, soil Olsen-P content was measured by 11 sampling intervals, and the phosphorus forms in soil were measured at the end of incubation. The effects of fertilization frequency on soil Olsen-P content, phosphorus fixation rate and phosphorus forms were analyzed, and characteristics on availability of phosphorus fertilizer under different fertilization times were clarified. The results showed that after 90 d of fertilization, the soil Olsen-P contents under 3 times of application increased significantly compared with that of once of application, and the increase rates at 3 Olsen-P levels were 21.0%, 13.5% and 9.4%, respectively. However, the phosphorus fixation rate decreased significantly, which were 8.0%, 6.8% and 10.5% at 3 Olsen-P levels, respectively. The Michaelis-Menten equation betterly fitted the process of soil phosphorus fixation. The maximum phosphorus fixation rate of once application was greater than that of 3 times application, but the time to reach 50% of the maximum phosphorus fixation rate was shorter than that of 3 times application. The phosphorus fixation rate decreased with the increase of Olsen-P levers under once application. Phosphorus fixation rate in high Olsen-P (49.7 mg·kg-1) soil was significantly reduced by 10.8%~ 12.4% compared with low Olsen-P (19.4~24.2 mg·kg-1) soil under 3 times application.When compared with once application, the content of labile P in soil increased by 6.8%~12.1%, and the content of non labile P decreased by 8.4% under 3 times application. This study showed that the 3 times application of phosphorus fertilizer could significantly improve the availability of soil phosphorus and reduce the fixation rate of phosphorus fertilizer; the higher soil Olsen-P content was, the smaller the proportion of phosphorus fertilizer was invalidated in soil; the 3 times application of phosphorus fertilizer could increase soil Olsen-P content, decrease phosphorus fixation rate and increase the content of labile P. These results had important directive significance to improve the utilization rate of phosphorus fertilizer, and provided theoretical basis for efficient and scientific application of phosphorus fertilizer. [ABSTRACT FROM AUTHOR]

In order to quantify the effect of biochar application on soil pH and provide theoretical basis for biochar application in soil improvement and fertility cultivation, based on the electronic databases CNKI, Wanfang and Web of Science, 413 biochar on soil pH case studies based on the keywords "Biochar", "Biochar", "soil pH" and "soil pH" were collected from 59 published literatures. Meta-analysis was implied to quantify the effect degree of soil conditions, biochar characteristics and biochar application amount on soil pH. The results showed that, compared with no biochar application, biochar application could significantly increase soil pH by 8.70%. In the strongly acidic soil (4.5 shell residue biochar (7.02%) > wood biochar (6.61%) . The biochar prepared at ≤400 °C had the best promotion effect of 15.26% under different pyrolysis temperatures, while, the increasing effect decreased with the increase of pyrolysis temperature, such as the pyrolysis temperature was between 400-700 °C. The increasing effect was higher in 3 months, then the increase gradually slowed down.These results indicated that in strongly acidic soil (4.5

Application of manure can increase soybean yield and soil fertility. There are significant differences in soybean yield and soil fertility in China due to the influence of region, application rate of manure, type of manure etc. However, the reasons for these differences are still not clear. In order to find out the effect of manure fertilizer application on soybean yield and soil fertility in different regions and management measures in China, and the main factors of yield increase effect, this study collected data on a national scale for integrated analysis. According to the searching criteria, 37 literatures including 119 groups of data on the effect of manure application on soybean yield and 11 literatures including 148 groups of data on the effects of manure application on soil nutrients were obtained. The enhanced boosted regression tree (BRT) model was used to quantify the importance of climate factors, soil properties and manure application measures on soybean yield increase. The average soybean yield increased by 12.9% after application of manure in different regions, with the highest yield in south China (18.7%) and followed by North China (14.8%), Northwest China (13.6%) and Northeast China (12.0%). When the application rate of manure was more than 5 000 kg⋅hm-2, the increase of soybean yield was 18.5%. Soybean yield increased by 24.9% after the application of cow manure, followed by the application of pig manure (17.6%), commercial manure (15.3%), chicken manure (12.7%) and manure (8.8%). The average soybean yield was 2 224 kg⋅hm-2 with no fertilizer, whereas it increased by 20.4% to the amount 2 518 kg⋅hm-2 with applying manure alone. The average soybean yield was 2 259 kg⋅hm-2 under the application of chemical fertilizer, whereas it increased by 9.1% to the amount 2 558 kg⋅hm-2 under the combined application of manure and chemical fertilizer. Manure application significantly increased soil available P (43.5%), total P (13.3%) and organic matter (11.0%), but had no significant effect on soil available K (9.4%), alkali hydrolyzable nitrogen (3.4%), pH (2.1%) and total K (1.2%). Based on the BRT results, the BRT model explained 52.83% of soybean yield differences in China. Among them, the application rate of manure had the greatest impact on soybean yield, accounting for 47.0% of the variation, followed by soil properties (41.0%) and climate factors (12.0%). In general, the application of manure (including the single application of manure and combined application of manure and chemical fertilizer) could significantly increase soybean yield, with the largest increase in South China and with the highest increasing production benefit under the application of cow manure. Soybean yield was mostly affected by the application rate of manure. Additionally, the available P, total P and organic matter contents in soybean soil significantly increased under the application of manure. [ABSTRACT FROM AUTHOR]