The effect of optimizing chemical fertilizers consumption structure to promote environmental protection, crop yield and reduce greenhouse gases emission in China

Potassium silicate and vinasse enhance biometric characteristics of perennial sweet pepper (Capsicum annuum) under greenhouse conditions

An effective strategy for enhancing fruit production continuity during extended sweet pepper season involves adopting innovative biostimulants such as potassium silicate (PS) and vinasse. Adjusting PS and vinasse concentrations are crucial for maintaining the balance between vegetative and fruit growth, particularly in sweet pepper with a shallow root system, to sustain fruiting over prolonged season. However, the interaction between PS and vinasse and the underlying physiological mechanisms that extend the sweet pepper season under greenhouse conditions remain unclear. This study aimed to investigate the impact of PS and vinasse treatments on the yield and biochemical constituents of perennial pepper plants cultivated under greenhouse conditions. For two consecutive seasons [2018/2019 and 2019/2020], pepper plants were sprayed with PS (0, 0.5, and 1 g/l) and drenched with vinasse (0, 1, 2, and 3 l/m3). To estimate the impact of PS and vinasse on the growth, yield, and biochemical constituents of pepper plants, fresh and dry biomass, potential fruit yield, and some biochemical constituents were evaluated. Results revealed that PS (0.5 g/l) coupled with vinasse (3 l/m3) generated the most remarkable enhancement, in terms of plant biomass, total leaf area, total yield, and fruit weight during both growing seasons. The implementation of vinasse at 3 l/m3 with PS at 0.5 and 1 g/l demonstrated the most pronounced augmentation in leaf contents (chlorophyll index, nitrogen and potassium), alongside improved fruit quality, including total soluble solid and ascorbic acid contents, of extended sweet pepper season. By implementing the optimal combination of PS and vinasse, growers can significantly enhance the biomass production while maintaining a balance in fruiting, thereby maximizing the prolonged fruit production of superior sweet pepper under greenhouse conditions.

Study of the utilization of main crop straw resources in Southern China and its potential as a replacement for chemical fertilizers

Although straw returning to the field (SRTTF) is conducive to promoting sustainable agricultural production and protecting the environment, straw resources are still wasted due to the lack of suitable straw-returning technology in southern China. Based on the statistical yearbook and a large number of studies, different methods were used to calculate the total straw resources and SRTTF potential, and differences in these methods were compared. The results indicate that the total amount of straw resources in southern China in 2021 was 3.35×108 t. The nutrient content of K2O in the straw accounted for the highest proportion of total nutrient resources (63.66%), followed by N (26.88%) and P2O5 (9.46%). In theory, total SRTTF could replace almost all K2O and part of N and P2O5, indicating that the nutrient substitution potential of SRTTF was high. It is suggested that the SRTTF method be adopted in the middle and lower reaches of the Yangtze River, which mainly uses direct returning (DR) supplemented by indirect returning (IDR). In southeast China, straw returning is carried out by the combination of IDR and IR. In southwest China, straw returning is mainly carried out by IR and supplemented by MDR. This study will provide theoretical support for the government to formulate straw-returning policy.

Study on N application and N reduction potential of farmland in China

The frequent occurrence of extreme weather in recent years poses a significant threat to food production. Ensuring food production and rationalizing the use of agricultural resources require addressing the problem of the improper application of chemical fertilizers. Several effective measures have been implemented in China to reduce agricultural non-point source pollution. Among them, the reduction of excessive nitrogen fertilizer application proves to be the most effective approach in controlling surface pollution from cultivation. Currently, it is crucial to clarify and quantify crop nutrient fertilizer requirements while evaluating the potential for reducing nitrogen fertilizer usage in China. Nitrogen requirements for major crops grown in China were assessed based on the theory of crop nutrient balance, assuming constant grain production as a guarantee. In this paper, we analyze the potential for nitrogen reduction through short-term, medium-term, and long-term scenario predictions. The results show that in the next 3 years, China has a reduction potential of 34.98%, but this potential is not sustainable. Over the next 10 years, there is a reduction potential of 15.04%, with most provinces experiencing a balanced state of soil nitrogen cycling. Hainan, Beijing, Shaanxi, and Fujian have higher reduction potential, with possible reductions of 69.95%, 64.14%, 60.72%, and 54.10%, respectively. However, there are still provinces in China where nitrogen fertilizer is insufficient, leading to soil nitrogen consumption. Specifically, Heilongjiang, Jiangxi, and Shandong Provinces need to increase their nitrogen fertilizer applications by 87.00%, 35.97%, and 8.31%, respectively. The long-term scenario analysis over the next 30 years shows a reduction potential of 40.96%. Among the regions analyzed, Hainan, Beijing, Shaanxi, Fujian, and Ningxia have higher nitrogen fertilizer reduction potentials, with values of 78.97%, 78.48%, 74.25%, 67.87%, and 67.72%, respectively. However, Heilongjiang Province still needs to increase nitrogen fertilizer application by 44.20% to address soil nitrogen depletion. Conversely, Tibet and Qinghai, with high organic fertilizer yields, lower chemical fertilizer usage, and low nitrogen loss coefficients, are well-suited for organic agriculture development. For areas with high organic fertilizers usage and a risk of fertilizer loss, we recommend implementing the organic-inorganic mixed fertilization planting mode.