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Biochar application has been confirmed as an efficient way to increase the productivity of the agricultural system. However, the potential of biochar combined with reducing fertilization on the yield, and the fertilizer utilization efficiency of the rice (Oryza sativa) farming system on acidic soil remains to be further studied. Field micro-plot experiments with two factors were performed in 2018 and 2019 to evaluate the responses of the rice yield and nutrient utilization to the combined application of biochar (60, 80, and 100 t/ha) and fertilizer reduction (70%, 85%, and standard doses of N-P-K fertilizer). Taoyouxiangzhan and Taiyou 553 were used in the late growing season of 2018 and 2019, respectively. The results showed that compared with the control without adding biochar under standard fertilization, 70% doses of fertilizer application had no negative effects on the yield and the N, P, and K accumulation of rice after biochar application. K accumulation of rice increased with the increase of biochar application. The partial productivity of N, P, and K fertilizers increased as the fertilizer was decreased. The agronomic efficiency of N, P, and K fertilizers significantly increased after the combined applications of biochar and fertilizer. In both years, micro-plots with 70% doses of fertilizer had the highest N and P physiological efficiency, as well as K physiological efficiency in 2019. Compared with the control under standard fertilization, utilization efficiency of N, P, and K fertilizer under different biochar and fertilizer combinations significantly increased by 34.24~75.48%, 27.44~84.84%, and 78.52~166.70%, respectively. To sum up, biochar can partially substitute fertilizer for rice production in acid paddy fields in southern China. When the amount of biochar added is ≥60 t/ha, 70% doses of fertilizer application can still ensure the nutrient absorption of rice, improve the fertilizer utilization efficiency, and ensure the stable yield of rice. [ABSTRACT FROM AUTHOR]

In arid and semi-arid regions, desertification threatens crop production because it reduces the soil's capacity to retain water and soil nutrients. At two fertilizer levels (90 kg N hm−2 and 45 kg P hm−2 and 270 kg N hm−2 and 135 kg P hm−2), the effects of soft rock (sand: soft rocks = 3:1) and biochar (4500 kg hm−2) applications on soil moisture, soil nutrients, and millet (Setaria italica L.) photosynthesis, yield, and its agronomic traits (biomass, thousand kernel weight, harvest index) were investigated in a field experiment in the Mu Us Sandy Land of China in 2018–2019. The addition of biochar and soft rock singly increased soil water content, alkali-hydrolyzed nitrogen (AN), total nitrogen (TN) and phosphorus (TP), and organic matter content significantly, suggesting that their application may increase the nutrient and water holding capacity of soil. Application of biochar and soft rock singly increased the net photosynthesis rate of millet flag leaf, at the flowering stage, from 15.97% to 56.26%. Biochar and soft rock application increased the yield range (2109.0 kg hm−2 to 5024.7 kg hm−2) from 5.26% to 54.60% under the same fertilizer level. Correlation analyses showed grain yield was significantly correlated with photosynthesis rate at the flowering stage, which was significantly correlated with soil AN at flowering, soil TP at flowering and harvest, and soil TN at flowering. These results indicated that the application of biochar and soft rock singly could increase soil fertilizer holding capacity to improve the photosynthesis rate at flowering, and, therefore, lead to improvements in crop yield. [ABSTRACT FROM AUTHOR]

The purpose of this study was to explore the effects of biochar application on soils in the main tobacco-producing areas in China. The study was conducted in four study regions in China, where the same three experimental treatments were set up in each area, including a control (CK), a treatment involving the application of chemical fertilizer (F), and a treatment involving the application of biochar (B). We analyzed the basic physical and chemical properties, microbial diversity, and root system of tobacco plants. The results show that: Biochar increased the soil pH, which was most obvious in the study site in Shaowu City, Fujian Province (FUS), where the soil pH increased by 22.64% and 27.49% compared with soil under the CK and F treatments, respectively. Biochar increased the microbial biomass carbon (MBC) content, and increased the soil content of available nitrogen, phosphorus, and potassium; this effect was most obvious in FUS. The root activity in plots treated with biochar increased by 6.95% and 13.72% compared to the CK and F plots, respectively. Similarly, the number of root tips increased by 89.76% and 21.48% compared to the CK and F plots, respectively. In short, biochar improved the physical soil structure, increased the soil pH, and promoted the effectiveness of soil nutrients. Furthermore, biochar improved the bacterial soil diversity, enriched the population structure of soil bacteria, and promoted the healthy development of flue-cured tobacco roots. However, the demand for and types of biochar suitable for use in different tobacco-planting soils need further study. [ABSTRACT FROM AUTHOR]