Effective, economical and feasible remediation technology of heavy metal pollution in farmland is an important research concentration in the field of farmland soil remediation. In order to investigate the remediation effects of formula fertilizer and biochar on cadmium (Cd)–plumbum (Pb) contaminated farmland, blank (CK), lime (SH), biochar (SWT), formula fertilizer (FL), and biochar + formula fertilizer (FS) were set up in Cd–Pb contaminated farmland. The results demonstrated the following: (1) Compared with CK, SWT and FS increased the yield by 11.21% and 15.00%, respectively, which was significantly higher than other treatments. (2) The concentrations of Cd and Pb in maize kernels under all treatments were lower than the limited value stipulated by GB 2762-2022 in China. Compared with CK, FS reduced the concentration of Cd and Pb in maize kernels by 24.96% and 31.46%, respectively, which were the most significant. All the treatments can reduce the concentrations of Cd and Pb in maize cob and straw and inhibit the transfer of Cd and Pb from the lower part of the maize field to the overground part. (3) FL, SWT, and FS increased soil pH by 0.17, 0.10, and 0.19 units, respectively. FS can reduce the concentrations of available cadmium (DTPA-Cd) and available lead (DTPA-Pb) significantly, which are 31.05% and 38.57% lower than CK, respectively. (4) Each treatment can reduce the extraction state and reducible state of weak acid Cd and Pb in soil, while increasing the proportion of oxidizable state and residual state. FL and FS significantly increased the percentage of residual Cd and Pb by 18.00% and 24.32%, respectively, and 33.33% and 37.76%, respectively. (5) FL (1.747) and FS (1.679) were relatively higher than CK in input/output. In conclusion, the combined application of biochar and formula fertilizer in Cd/Pb polluted farmland can effectively reduce the concentration of Cd and Pb in maize and has high economic benefits and practicability.

Plant extraction is a thorough remediation method to remove heavy metals from soil. Chelating agents can enhance the extraction effect of heavy metals from soil by plants. In this study, low molecular weight organic acids (LMWOAs), such as citric acid (CA), tartaric acid (TA) and polyaspartate (PASP), were added to the farmland soil contaminated with Cd and Pb and combined with corn to enhance the absorption and extraction of Cadmium (Cd) and Plumbum (Pb). The effects of LMWOAs on the growth and yield of maize, Cd and Pb concentrations in each part of maize, rhizosphere soil pH, total cadmium and lead content and DTPA-Cd and Pb concentrations were studied. The enrichment, transport and extraction ability of maize were analyzed, and calcium chloride (CaCl2) was compared. The results showed that: (1) Exogenous LMWOAs increased the biomass and yield of maize compared with no material added (CK), and CA increased the yield of maize by 6.33%. (2) Exogenous LMWOAs promoted the uptake of Cd and Pb in all parts of maize, and the distribution of Cd and Pb in all organs was as follows: straws > roots > maize cobs > kernels and roots > straws > maize cobs > kernels. The Cd and Pb concentrations in maize kernels were in line with GB 13078-2017 in China, which could be used as feed maize. (3) Exogenous LMWOAs enhanced the enrichment of Cd and Pb in maize straws and roots. PASP had a good enrichment effect on Cd and Pb. CA and CaCl2 could enhance the transport capacity of Cd and Pb from maize roots to straw. (4) Compared with CK, the total amount of Cd and Pb in rhizosphere soil decreased by 6.93–26.99% and 2.74–6.79%, respectively. LMWOAs could promote the concentration of DTPA-Cd and Pb in rhizosphere soil, and PASP had the most significant increase in DTPA-Cd and Pb in rhizosphere soil. Compared with CK, the soil pH value decreased by 0.03–0.14 units. LMWOAs can enhance the removal of heavy metals from maize, and PASP has the most significant comprehensive effect.

Eutrophication is increasing with intensive agricultural activities as a global environmental challenge, especially in developing countries. In order to establish the effects of long-term reducing fertilization and straw returning on nitrogen (N) and phosphorus (P) loss in surface runoff due to intensive cultivation in the Yangtze River basin, China, we conducted a 7-year field pilot experiment with rice-wheat rotation in the fifth largest fresh water lake basin. The treatments included no fertilization (CK), conventional fertilization (Conv. Fert.), optimized fertilization (Optim. Fert.), nitrogen reduction by 30% (70%N), P reduction by 50% (50%P), and N reduction by 30% and P reduction by 50% + straw returning (70%N50%P+Straw). Results showed that the average wheat yields in reducing fertilizer treatments (70%N, 50%P, and 70%N50%P+Straw) slightly decreased by 1.21%, 5.26%, and 1.17%, respectively, compared to those with the optimized fertilizer, whereas average rice yields slightly increased by 3.71%, 0.64%, and 1.23%, respectively. However, the reducing fertilizer treatments (70%N50%P+Straw) significantly reduced the loss of N and P in surface runoff compared with Conv. Fert. and Optim. Fert. Total P and dissolved P in surface runoff water in rice seasons was predictable and modeled. The annual average N, P, and K fertilizer efficiency for rice-wheat rotation ranged in 21%–42%, 12%–38%, and 35%–53%, respectively. Considering the yields of rice and wheat along with eco-environmental benefits of reducing N and P loss in surface water, 70%N50%P+Straw treatment was the best treatment for Chaohu region. This long-term field study recommends the employment of the reduced chemical fertilizer by 30% N and 50% P in Chaohu basin for rice and wheat crops with the maximum reduction of runoff N and P and the highest fertilizer (N and P) efficiency with reasonable high crop yields. This is especially important for farmers in developing countries in achieving economical, ecological, and environmental benefits in sustainable modern agriculture to feed the increasing global populations.

We studied the influence and correlation of soil improvement, farmland ecological protection, soil fertilization, and field infrastructure construction on the quality grade of well-fertilized farmland in the engineering measures of well-fertilized farmland construction. Taking Xiao County of the Anhui Province as the study area, based on the software platforms of SPSS, ArcGIS10.6, and the county farmland resource management information system, we investigated the farmland quality changes of well-facilitated farmland before and after construction using the fuzzy evaluation method and analytic hierarchy process. We used principal component analysis and the gray relational method to analyze the impact and correlation of various engineering measures on farmland quality. The farmland quality grade in the study area was improved by a 0.59 grade after the construction of the well-facilitated farmland. Well-facilitated farmland construction engineering measures mainly affected the farmland quality through 12 factors, such as the soil bulk density, tillage layer texture, irrigation and drainage guarantee rates, forest network density, and field road accessibility. There is a strong correlation between these factors and the characteristics of farmland quality; the degrees of correlation were 0.865–0.610, respectively. The highest correlation degree was 0.939 between the deep plowing and deep loosening soil improvement project and the improvement of the well-facilitated basic farmland quality; this was followed by soil fertilization with an increased application of organic fertilizer, farmland ecological protection, and the field infrastructure project with correlations of 0.936, 0.857, and 0.563, respectively. Represented by the improvement of farmland fertility, the soil improvement project had the strongest impact on well-facilitated farmland quality. The soil fertility project, farmland ecological protection project, and the field infrastructure project were the second most important, with very close degrees of correlation.

The accumulation of heavy metals in rice is bound to affect human health and safety. In order to ensure food security, this study explores the effect of leaf surface regulation of zinc (Zn) fertilizer on the safety of rice in cadmium (Cd)-plumbum (Pb) polluted farmland. Through field experiments, the leaf surface control treatment of zinc fertilizer was set up, and the effects of leaf surface control of zinc fertilizer on rice yield, Cd and Pb concentration in different parts and zinc, nitrogen, phosphorus and potassium concentration in brown rice were studied in the growing period of rice. The results showed as follows: (1) Spraying twice or more in the growth stage of rice could increase the yield by 6.77–7.29% compared with the blank, which was significantly higher than that of single spraying in a certain growth stage. (2) After spraying zinc fertilizer on the leaf surface, Cd and Pb concentration in brown rice decreased by 29.52–56.01% and 11.10–28.34%, respectively, compared with CK. Two or more times of spraying can make Cd concentration in brown rice meet the Chinese standard GB 2762-2022, and one time of spraying can make Pb concentration in brown rice meet the standard. (3) Leaf surface control of zinc fertilizer could reduce the Cd enrichment ability of rice plant parts, and the Cd enrichment coefficient of brown rice was significantly reduced by 28.18–55.02%. Leaf surface control of zinc fertilizer can reduce Cd and Pb concentration in brown rice by reducing the transport ability of heavy metal Cd and Pb in rice roots to straw and then to brown rice. (4) The zinc concentration in brown rice was 18.16–20.68 mg·kg−1, which was 18.21–34.64% higher than that in CK, and the zinc enrichment effect was the most significant after spraying three times. Meanwhile, the nitrogen, phosphorus and potassium concentration in brown rice also increased with the increase of spraying times. By comprehensive analysis, the leaf surface control of zinc fertilizer can reduce the Cd and Pb concentration in rice, and the Cd and Pb concentration in brown rice can meet the Chinese standard GB 2762-2022 by spraying twice. At the same time, it can improve the concentration of zinc, nitrogen, phosphorus and potassium in brown rice, is feasible and has high economic benefits.