Although humic acid has been demonstrated to improve the quality of some soil types, the long-term effects of humic acid on soil under continuous cropping peanut are not fully understood. This study aimed to investigate the continuous effects of humic acid on the physicochemical properties, microbial diversity, and enzyme activities of soil under continuous cropping peanut. In this study, a three-year consecutive experiment of cropping peanut was conducted in the North China Plain. In addition to the equal nitrogen, phosphorus, and potassium inputs, humic acid treatment was applied with inorganic fertilizers. Compared with control experiments, humic acid increased the yield and quality of continuous cropping peanut. To elucidate the mechanism of humic acid affecting the soil quality, various soil quality indicators were evaluated and compared in this study. It was found that humic acid increased soil nutrient contents, including the total soil nitrogen, total phosphorus, total potassium, available nitrogen, available phosphorus, available potassium, and organic matter contents, which exhibited the maximum effect in the third year. Meanwhile, the urease, sucrase, and phosphatase activities in the soil significantly increased after treated with humic acid, of which the maturity period increased most significantly. The same results were observed for three consecutive years. Microbial diversity varied considerably according to the high throughput sequencing analysis. Specifically, the number of bacteria decreased while that of fungi increased after humic acid treatment. The abundance of Firmicutes in bacteria, Basidiomycota, and Mortierellomycota in fungi all increased, which have been reported as being beneficial to plant growth. In contrast, the abundance of Ascomycota in fungi was reduced, and most of the related genera identified are pathogenic to plants. In conclusion, humic acid improved the yield and quality of continuous cropping peanut because of improved physicochemical properties, enzymatic activities, and microbial diversity of soil, which is beneficial for alleviating the obstacles of continuous cropping peanut.

Overapplication of N and P and insuffi cient supply of K are considered primary reasons for restriction of yield improvement in the North China Plain. Optimized nutrient management practices based on soil testing and yield targets have been developed. Other large scale fi eld experiments have indicated that additional improvement for yield and nutrient use benefi ts is needed. Th e objective of this study was to evaluate the eff ects of the optimized nutrient management system on yield, nutrient uptake, nutrient utilization, and profi t in the North China provinces of Shanxi, Hebei, Shandong, and Henan. Treatments consisted of a check without fertilizer use (CK); a balanced, optimum nutrient application (OPT); the farmers' practice (FP); and a series of nutrient omission treatments (minus N, P, and K, respectively). Th e results indicated that the OPT optimized grain yield, nutrient use effi ciency, and profi tability. Maize (Zea mays L.) yield increased by 12.2% at Shanxi and 18.5% at Hebei, respectively. Inputs of N and P across the wheat (Triticum aestivum L.) and maize system at the four sites was reduced by 13% (266 kg N ha −1 ) and 45% (430 kg P 2 O 5 ha −1 ), while K input was increased by 43% (265 kg K 2 O ha −1 ). Th e OPT improved both measurements of nitrogen use effi ciency (NUE); agronomic nitrogen effi ciency (AE N ) and nitrogen recovery effi ciency (RE N ) in the majority of cases. Although the OPT tested in this study increased yields and nutrient uptake, there remains considerable potential to improve AE N and RE N further for this intensive winter wheat-summer maize rotation system.

Core Ideas Nutrient Expert is a new nutrient management approach and is confirmed for use in north‐central China.The continual feasibility of Nutrient Expert was evaluated through multiple‐point field experiments.This is the first report of Nutrient Expert on improving environmental benefits of winter wheat. Over application of N and P and poor nutrient management have become a common practice on the North China Plain, and lead to low nutrient use efficiency (NUE) and serious environmental problems. Thus, nutrient management for crops must be improved. In this study, 315 field experiments were conducted from 2011 to 2014 in major winter wheat domains in north‐central China to validate the continual feasibility of the Nutrient Expert (NE) system for improving NUE and reducing greenhouse gas (GHG) emission. The NE system significantly increased grain yield, profitability, and NUE, and decreased GHG emission. Compared with farmers’ practice (FP), the NE treatment reduced N and P inputs by 41.4 and 30.1% (115 kg N ha−1 and 36 kg P2O5 ha−1), respectively, and increased K input by 51.5% (25 kg K2O ha−1). Compared with the FP and soil testing (ST) treatments, the NE treatment increased agronomic efficiency of nitrogen (AEN) by 70.0 and 13.3%, recovery efficiency of nitrogen (REN) by 73.8 and 13.3%, and partial factor productivity of nitrogen (PFPN) by 58.5 and 22.2%, respectively. Compared with the FP and ST treatments, the NE treatment reduced total N2O emissions by 54.8 and 26.3%, total GHG emissions by 44.8 and 22.9%, and GHG emission intensity by 45.8 and 22.0%, respectively. These results confirmed that NE is an effective method to make fertilizer recommendations for wheat in north‐central China and has the potential to improve yield, NUE, and profitability, with low environmental pollution.

Imbalanced fertilization has caused lower yield and nutrient use efficiency for radish ( Raphanus sativus L.) production in China. Estimating nutrient requirements for radish is crucial in optimizing fertilization to resolve the problem. On-farm experiments in the radish-growing regions of China from 2000 to 2017 were collected to investigate the relationship between fleshy root yield and nutrient accumulation in radish plant using the Quantitative Evaluation of the Fertility of Tropical Soils (QUEFTS) model. The QUEFTS model predicted a linear increase in fleshy root yield if nutrients were taken up in balanced amounts until yield reached about 60%–70% of the potential yield. The balanced N, P, and K requirements in radish plant simulated by the QUEFTS model were 2.15, 0.45, and 2.58 kg to produce 1000 kg of fleshy root, and the corresponding internal efficiencies (IEs, kg fleshy root per kg nutrient in total plant dry matter) for N, P, and K were 465.1, 2222.2, and 387.1 kg kg −1 . The simulated balanced N, P, and K removal by fleshy root to produce 1000 kg fleshy root were 1.34, 0.30, and 1.93 kg, respectively. Approximately 62%, 67%, and 75% of N, P, and K in radish plant were presented in the fleshy root and removed from the soil. Field validation experiments confirmed the consistency between the observed and simulated nutrient uptake values. The QUEFTS model was proven to be effective for estimating nutrient requirements of radish and will contribute to develop fertilizer recommendations for radish cultivated in China.

Background Allium fistulosum L. has good nutritional value and is cultivated worldwide as an efficacious traditional medicinal plant. Its biological activities are attributable to its phytochemicals. Nitrogen is an essential nutrient for plant growth and development; however, the effect of nitrogen levels on the level of active components in this species is not well understood. Methods In this study, using urea fertilizer, we investigated the effects of different nitrogen levels (N0, N1, and N2 at 0, 130, and 260 kg/ha, respectively) on the phytochemical constituents , and antioxidant and anticancer properties of A. fistulosum. Results The results suggested that nitrogen fertilizers have a significant effect on the level of total phenols and flavonoids. The analysis of the antioxidant capacity revealed that the lowest IC50 values corresponded to plants treated with the highest nitrogen concentration. Anticancer activity was investigated against cancer cell lines (HeLa and HepG2), and the extracts of A. fistulosum treated with a high nitrogen level showed the highest antiproliferative effect. Collectively, our results suggest that nitrogen fertilizer application enhanced the quality of A. fistulosum, particularly its health benefits.