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Diminishing soil fertility and crop productivity due to traditional intensive cultivation has prompted the use of straw and manure to improve soil health in Northeast China. However, few comparative studies have explored the influence of varying straw and manure incorporation depths on crop growth. A field experiment in the rainfed black soil regions of Gongzhuling and Keshan assessed the effects of deep (30 cm) and shallow (15 cm) incorporations of straw and manure on soil fertility, maize root growth, and maize productivity. Deep incorporations, via subsoiling tillage (DST) and deep-plow (DDT) tillage, enhanced soil water storage of 30–100 cm soil layer during periods of low rainfall, improved the availability of nutrients (nitrogen, phosphorus, and potassium) and soil organic matter content, especially in deeper soil, compared to shallow incorporation using rotary tillage (SRT). Both DST and DDT induced a larger rooting depth and a higher fine root (diameter class 0–0.5 mm) length density by 31.0% and 28.9%, respectively, accompanied by reduced root turnover. Furthermore, the sub-surface foraging strategies of roots under the DST and DDT treatments boosted the total nitrogen, phosphorus, and potassium uptake (6.5–17.9%) and achieved a higher dry mass accumulation during the later growth period, thus leading to notable improvements in the 100-kernel weight and yield (16.1–19.7%) and enhancing water- and nutrient-use efficiencies by 2.5–20.5%. Overall, compared to shallow incorporation, deep incorporation of straw and manure significantly enhances root growth and spatial distribution of soil water and nutrients, which has great potential for increasing maize yield in rainfed agricultural areas. [ABSTRACT FROM AUTHOR]

Phosphorus (P) leaching from excessive P application is the primary pathway of P losses in agricultural soils. Different P fertilizer practices have mixed effects on P leaching. We conducted a meta-analysis of the relevant literature regarding the response of crop yields, soil-available P (AP), and total P (TP) leaching to reduced P input (RP) and an inorganic-organic combination fertilizer (NPKM) for different agricultural land-use types. Compared to conventional P application (CP), RP (10~90% reduction) did not reduce crop yields in vegetable fields (experiments were 1~4 years) but significantly reduced cereal yields by 4.57%. Compared to chemical fertilizer (NPK), NPKM significantly increased cereal yields by 12.73%. Compared to CP, RP significantly reduced AP at 0~60 cm in vegetable and cereal fields. The greatest reduction occurred at 20~40 cm in vegetable fields (40.29%) and 0~20 cm in cereal fields (34.45%). Compared to NPK, NPKM significantly increased the AP at 0~60 cm in vegetable fields, with the greatest increase (52.44%) at 20~40 cm. The AP at 0~40 cm in cereal fields significantly increased under the NPKM treatment, with the greatest increase at 0~20 cm (76.72%). Compared to CP, RP significantly decreased TP leaching by 16.02% and 31.50% in vegetable and cereal fields, respectively. Compared to NPK, NPKM significantly increased TP leaching in vegetable fields (30.43%); no significant difference in leaching occurred in cereal fields. P leaching, in response to RP, was influenced by the P amounts applied (34.49%); soil organic matter (14.49%); and TP (12.12%). P leaching in response to NPKM was influenced by multiple factors: rainfall (16.05%); soil organic matter (12.37%); soil bulk density (12.07%); TP (11.65%); pH (11.41%). NPKM was more beneficial for improving yields in cereal fields with low soil fertility and lower P-leaching risks. [ABSTRACT FROM AUTHOR]

Understanding the effects of a fertilization regime on the long-term accumulation and transformation of soil phosphorus (P) is essential for promoting the development of sustainable management of soil P. Based on a 29-year field experiment in Mollisol, the compositions and changes of P forms using a modified Hedley sequential extraction method, solution 31P-NMR and P K-edge XANES and soil properties were investigated under continuous mono maize with and without manure (NPKM and NPK). Results showed a stronger positive related coefficient between soil total P and labile P, and mid-labile P fraction was found in NPKM than in NPK treatment. It indicated NPKM could improve the availability of soil accumulated P and reduce its transformation to stable P. Accumulated inorganic P (Pi) was dominated by aluminum phosphate (Al-P) and monobasic calcium phosphate monohydrate (MCP) for NPK treatment, Al-P, MCP, and tricalcium phosphate for NPKM treatment with XANES analysis, which contributed to the P availability in Mollisol. Moreover, the proportion of IHP with XANES and ratio of orthophosphate diesters to monoesters in NPK compared to NPKM indicated the higher Po lability with NPK treatment. Pi, especially NaHCO3-Pi and NaOH-Pi, were the potential sources of resin-Pi. Soil organic matter (SOM), organic-bound iron, and alumina oxide (Fep + Alp) showed significant influence on the transformation of P forms. Our research suggested that due to the rise in SOM and Fep + Alp, the fertilization regime significantly increased most highly active soil P fractions, especially in NPKM treatment. This work gives new insight into sustainable P management, which benefits the reduction in soil P accumulation. [ABSTRACT FROM AUTHOR]

Negative pressure irrigation (NPI) is an important water management strategy that can improve crop yields and water use efficiency (WUE). However, because NPI is affected by vital factors, such as negative pressure values, soil properties, and fertilization dosages, there is a lack of systematic analyses of the application effects of NPI on various crops. Hence, this study collected the results of 44 published studies and established the validity of 142 crop yields, 121 WUEs, 138 crop qualities, and 138 crop nutrient statuses in a database for NPI systems. The meta-analysis method was used to analyze NPI in comparison to conventional irrigation (CI) conditions. The results showed that the NPI yields and WUEs significantly improved by 17% and 63% compared to those of CI, respectively. Meanwhile, the negative pressure values were −2~−5 kPa; the improvement effects on yields were the best; and the WUEs exhibited the highest performance with negative pressure values of −6~−10 kPa. NPI promoted crop quality and plant nutrient uptakes under the appropriate NPI conditions. The synergistic impacts for sandy loam, alkalescent soils, and leafy vegetables were greater than for clay loam, neutral soils, and fruit vegetables under NPI conditions. Simultaneously, it was shown that the soil available phosphorus content and application of P fertilizer have a greater impact on NPI and CI crop yields. Therefore, the meta-analysis demonstrated the impacts of NPI on crop yields, WUEs, quality, and nutrient absorption, and quantified the effects of NPI on crop growth under various conditions, which provides an important water-saving technology for greenhouse production. [ABSTRACT FROM AUTHOR]