The global phosphate (P) rock shortage has become a significant challenge. Furthermore, the misalignment between crops, soil, and P usage exacerbates P rock wastage in agriculture. The distinctions among various types of phosphorus fertilizers influence the phosphorus cycle, which subsequently impacts biomass, the number of grains per ear, the weight of a thousand grains, and, ultimately, the overall yield. In a four-year field experiment conducted from 2017 to 2021, we assessed the impact of various P fertilizer types on crop yield in a continuous wheat–maize rotation system. Prior to planting the crops, P fertilizers were applied as base fertilizers at a rate of 115 kg P₂O₅ ha⁻¹ during the wheat season and 90 kg P₂O₅ ha⁻¹ during the maize season. Additionally, nitrogen (N) was applied at rates of 120 kg ha⁻¹ for wheat and 180 kg ha⁻¹ for maize. The P fertilizers used included ammonium dihydrogen phosphate, ammonium polyphosphate, calcium–magnesia phosphate, ammonium phosphate, and calcium superphosphate. Urea was used as the N fertilizer with a split application—60% at planting and 40% at the jointing stage for wheat or the V12 (twelve leaf collar) stage for maize. The results showed that different P fertilizers increased the average yield of wheat and maize by 21.2–38.0% and 9.9–16.3%, respectively. It was found that ammonium polyphosphate, calcium superphosphate, and monoammonium phosphate were more suitable for application in a summer maize–winter wheat rotation system on loess soil.

Biochar is currently widely used as the adsorbent for phosphorus (P) removal from wastewater. Cheap and green modified materials and efficient preparation methods are the key to obtain efficient and economical engineering biochar. Conventional salt solution and chemical impregnation are common methods for preparing engineered biochar. However, this preparation method is not environmentally friendly or cheap due to the price of salt solutions and the solvent treatment process for chemical impregnation. In this article, Ca-laden biochar was prepared using peanut shells as carbon base materials and discarded eggshells as calcium source. Two methods (ball milling and chemical impregnation) of building the Ca-laden biochar were compared from the perspective of the characterization of biochar, the adsorption performance and the economic cost. The composition and structure of biochar were analyzed by the element content, functional group, X-ray diffraction, energy spectrum and electron microscope scanning etc. The adsorption behavior of biochar was tested in different environments (pH and temperature). The results revealed that the capacity of P adsorption by the Ca-modified biochar was higher than the adsorption by raw biochar, and that the prepared Ca-laden biochar has a wide working environment. Moreover, the Ca-laden biochar prepared by ball milling has a higher specific surface area and more porosity. The Ca-modified biochar through ball milling has a higher amount of adsorbed P than that of through chemical impregnation. This work not only creates a novel method for making excellent P adsorbents, but also offers an environmentally friendly use for agricultural eggshells and peanut shells.

Various phosphorus (P) fertilizers are commonly utilized in agricultural production on the Loess Plateau. However, there exists a widespread issue of improper matching between P fertilizers, crop types, and soil types. This study proposes a scientifically based approach to managing phosphate fertilizer through a matching experiment. A field experiment was conducted to investigate the effects of different P fertilizers on soil P profiles in a wheat–corn rotation between October 2017 and September 2021. The experiment adopted a randomized block design. P fertilizer was applied as a basal fertilizer at rates of 115 kg P₂O₅ ha⁻¹ during the wheat season and 90 kg P₂O₅ ha⁻¹ during the maize season. Nitrogen (N) fertilizer application rates were 120 kg N ha⁻¹ for wheat and 180 kg N ha⁻¹ for maize. N fertilizer was divided into two applications, with 60% applied at pre-planting and 40% at the jointing stage of wheat or the V12 stage of maize. P fertilizer variants utilized in the study included ammonium dihydrogen, ammonium phosphate, calcium-magnesia phosphate fertilizer, calcium superphosphate, and ammonium polyphosphate. The transformation process of phosphate was examined, revealing that the commonly considered dominant diammonium phosphate fertilizer was not the optimal choice in this production system. Ammonium polyphosphate, calcium superphosphate, and ammonium dihydrogen were deemed more suitable for application in Loess soil. Furthermore, an analysis was conducted on the relationship between P fractions, soil properties, and soil Olsen-P. This research emphasizes the significance of strategic phosphate fertilizer use in agriculture to ensure efficient production and to help address the global P scarcity.

In the process of rice cultivation, fertilizer reduction can effectively reduce the concentration of phosphorus (P) in overlying water and leaching water. In this study, the variation characteristics of P in overlying and leaching water under the conditions of fertilizer reduction and straw application and its impact on the environment were studied through a two-season rice field experiment. Four treatments were set, including no fertilizer without straw (CK), conventional fertilization (CF), 20% reduction in nitrogen (N) and P fertilization (RF), and 20% reduction in N and P fertilization with the wheat straw (RFWS). The results showed that RF could effectively reduce the risk of P loss due to its ability to decrease the concentration of P in overlying and leaching water. RFWS increased P concentrations in overlying and leaching water of rice fields. Total dissolved phosphorus (TDP) was the main form of total phosphorus (TP), and soluble reactive phosphorus (SRP) was the main form of TDP. The concentration of TP, TDP, and SRP in the overlying and leaching water peaked on the first day after fertilization, and then gradually decreased. The high-risk period of P loss was 0 to 10 days after fertilization. This study could provide appropriate strategies to reduce the risk of P loss during local rice cultivation and protect local water resources from eutrophication.

In modern agriculture, small peptide fertilizers (SPFs) have emerged as a promising tool to enhance crop growth, yield, and stress resilience. However, the influence of raw materials and innovative preparation methods on SPF characteristics and agronomic performance remains underexplored. This study introduces instant catapult steam explosion (ICSE), a novel thermomechanical technology, for synthesizing SPFs from fish, soybean meal, and sheepskin. The molecular, chemical, and nutritional properties of the SPFs were then characterized using methods including gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), and HPLC/LC-MS. The research aims to characterize the molecular, chemical, and nutritional profiles of resulting SPFs and evaluate their effects on rice and rapeseed growth, yield, and nitrogen use efficiency (NUE). ICSE-generated SPFs exhibited distinct properties based on raw materials. Fish-derived SPF1 had a narrow molecular weight distribution, high small peptide content (573 mg g⁻¹), and free amino acids (0.478 mg g⁻¹), while sheepskin-derived SPF3 showed the lowest values (386 mg g⁻¹ and 0.366 mg g⁻¹, respectively). Fourier-transform infrared spectroscopy (FTIR) confirmed the presence of peptide bonds and functional groups, with variations in peak intensities reflecting differences in raw materials. Field trials revealed that SPF1 significantly improved rice and rapeseed growth parameters, including plant height, SPAD values, and flag leaf area, compared to controls. Yield increases of 10.36% (rice) and 11.74% (rapeseed) were observed for SPF1, alongside the highest NUE (42.3–43.4%). Soybean meal-derived SPF2 showed moderate performance, while SPF3 had minimal effects. These findings validate ICSE for sustainable SPF production and emphasize the importance of selecting raw materials to optimize fertilizer outcomes and enhance crop productivity.

The intensive management of double-cropping rice systems relies on high inputs of fertilizer and labor to sustain high yields. However, this leads to substantial reactive nitrogen (Nr) losses and severe environmental degradation. Although both enhanced-efficiency nitrogen fertilizers (EENFs) and deep placement are recognized for mitigating specific Nr loss pathways within individual seasons, robust field evidence for their combined, cross-seasonal efficacy across multiple loss pathways remains scarce. This study assessed the integrated agronomic, environmental, and economic performance of deep-placed EENFs in a double-rice cropping system. The EENFs included stabilized urea (SU) and controlled-release urea (CRU). Nitrogen release patterns differed significantly between fertilizers: SU showed strong season-dependent dynamics, while CRU provided a stable, consistent supply across both early and late rice seasons, achieving superior synchronization with crop nitrogen demand. Crucially, deep placement was indispensable for reducing environmental risks. The integrated strategy of deep-placing CRU (CRUD) facilitated a “spatiotemporal dual regulation” of nitrogen, spatially mitigating surface losses via deep placement and temporally synchronizing nutrient release with crop demand via the controlled-release mechanism. Compared with conventional surface-applied urea, CRUD significantly enhanced grain yield (16.1% and 17.5%), increased nitrogen recovery efficiency (41.5% and 67.4%), reduced total N losses (42.3% and 31.3%), and improved net economic benefits (35.0% and 30.9%) in early and late rice, respectively. It provides a concrete, actionable solution for advancing sustainable intensification in double-cropping rice systems, contributing directly to Sustainable Development Goals (SDGs).