Applications of organic manure increased maize (Zea mays L.) yield and water productivity in a semi-arid region (2024)

With an increasing concern of soil health and sustainable development, organic manure application has been readdressed in recent years. In Northeast China, the agricultural industry is highly developed and organic manure resources are abundant, but soil degradation is serious due to extensive expansion of cultivation. Currently, limited information is available on how soils with various degradation degrees respond to long-term manure fertilization. Given that, a comparative study was conducted based on soil functional assessment of croplands with over 35 years of manure fertilization (maize straw compost, SA; cattle manure, CA) and various degradation degrees (none, light, moderate, and heavy). Soils in these croplands were loess-derived Mollisols and concentrated on a gentle to flat slope. Except for the difference in manure fertilization (SA and CA), similar field managements were adopted for these croplands during the past 35 years. Results showed that the impacts of erosion degradation and manure fertilization on soil physical structure lasted across the whole profile (0 ∼ 120cm), while their impacts on soil nutrient properties were concentrated in shallow layers (<50cm). Meanwhile, erosion degradation dominated 17.9% of the variance of soil physical structure, and soil profile depth contributed to 15.9% of soil nutrient variation. According to field validation regarding soil erosion modulus and crop yield, principal component analysis (PCA) with a nonlinear scoring method showed a good performance on the integrated soil functional index (ISI) assessment in this study area. The ISI of these croplands was found to be minimally characterized by BD, SOC, TN, AK, sand content, and CEC (R² >0.64, p<0.001). In addition, manure fertilization could significantly improve the ISI and maize yield for degraded soils, but had a slight impact on these two indicators for non-degraded soils. In terms of contribution to ISI improvement, SA (1.79% ∼ 283.73%) generally outperformed CA (4.53% ∼ 212.83%), while the latter was more effective in altering soil structure in deep layers (>70cm). Generally, the ISI and maize yield were more susceptible to erosion degradation than manure fertilization. The obtained results provide useful information for a better cropland management in Northeast China.

Water scarcity as well as soil degradation and environmental problems potentially caused by excessive application of chemical fertilizers are major challenges to agricultural production in semi-arid areas. It is crucial to explore a suitable and eco-friendly strategy to achieve sustainable production of maize with high crop water productivity and nitrogen use efficiency. Here, a two-year field experiment with three irrigation levels of W1 (220mm), W2 (140mm) and W3 (60mm), and five fertilization types of no fertilizer (CK), chemical fertilizer (CF), bio-fertilizer combined with CF (CFB), organic fertilizer combined with 70% CF (CFO) and bio-fertilizer combined with CFO (CFOB) was conducted to investigate the effect on dry matter, N uptake and remobilization, grain yield, crop water productivity, nitrogen use efficiency and economic benefits of maize in 2021 and 2022. The results showed that the W2 and W3 decreased in the leaf area index, photosynthetic rate, dry matter accumulation, the maximum dry matter accumulation rate and actual crop evapotranspiration. Under W1 condition, the CFB improved the growth of maize, increased the dry matter and nitrogen accumulation and yield, with 8.1% and 7.4% higher than CF in 2021 and 2022, respectively. Under deficit irrigation (W2 and W3), CFOB significantly increased the leaf area index, photosynthetic rate, dry matter accumulation at later growth stage, in addition, CFOB increased the post-silking N uptake and the percentage in total N content, finally improved the grain yield with 23.8% and 22.8% under W2, 22.5% and 25.7% under W3 higher than that of the CF in 2021 and 2022, respectively. Irrigation and fertilizer showed a coupling effect on grain yield, crop water productivity, agronomy efficiency and nitrogen use efficiency. Overall, the CFOB under moderate deficit (W2) exhibited the highest water productivity, nitrogen use efficiency and economic benefits, as well as maintained the high yield, could be a promising approach to sustainable development of local maize.

Water stress, improper fertilization practices, and agricultural waste pollution severely reduce soil fertility and limit agricultural sustainability on the Loess Plateau. Organic fertilizer application is an efficient method for improving soil water and nutrient availability and grain yield in semi-arid and arid areas. However, the impact of bio-organic fertilizer derived from agricultural waste on soil characteristics and wheat yield and the optimum bio-organic fertilizer substitution rate in semi-humid drought-prone areas remain unclear. A two-year field study was conducted to explore the effect of combined bio-organic and chemical fertilizer application on soil moisture, hydraulic properties, soil structure, soil organic carbon (SOC), total nitrogen (TN), grain yield, and water productivity (WP). Six different treatments were designed: no fertilization (CK), conventional chemical fertilization (CF), and bio-organic fertilizer treatments substituting 25% (OF_25%), 50% (OF_50%), 75% (OF_75%), and 100% (OF_100%) of the chemical N fertilizer. From the seedling to over wintering stage, the OF_75% and OF_100% treatments generally improved soil water storage (SWS) and soil water content (SWC) within the 0–100cm soil layer compared to the CK and CF treatments across both growing seasons. Bio-organic fertilizer substitution significantly reduced soil bulk density by 4.0–5.6% and enhanced soil porosity by 4.2–5.9% in the 0–40cm soil layer. Moreover, bio-organic fertilizer substitution significantly increased soil saturated hydraulic conductivity and water content, improved aggregate size distribution, and enhanced SOC and TN contents in both years. The OF_75% treatment produced the highest aboveground biomass, yield components, grain yields, and WP, attributed to the improved soil physical environment and nutrient contents. Notably, the OF_75% treatment increased the average wheat yield and WP by 21.1% and 24.9%, respectively, relative to the CF treatment across both growing seasons. The measured soil properties strongly correlated with wheat yield, yield components, and WP. Thus, the OF_75% treatment is an appropriate and promising fertilization management strategy to alleviate water stress, improve soil properties, and promote crop production in semi-humid drought-prone regions.

The plant–water relationship of maize under conservation practices needs to be assessed to quantify the effectiveness of the practices in conserving soil water for crop production. This study evaluated in three trials how straw and plastic film mulching and organic manure application could potentially change water fluxes in the root zone and increase maize yield. A mathematical model HYDRUS-1D was calibrated against the observed soil water content and drainage data to predict the water fluxes in the root zone soil. The model simulated soil water dynamics in the root zone with satisfactory performance (RMSE of 0.6–2.3%, CD of 0.37–1.41, NSE of 0.18–0.88, and R² of 0.62–0.91) during both the calibration and validation periods. The model predicted the observed drainage in a lysimeter with only a 5.5–11.7% bias and actual evapotranspiration (ET_c) with a 2.6–6.7% bias for the control conditions in all three trials when the model was provided with measured plant growth, soil properties, and weather data. Both measurement and modeling confirmed that mulching augmented soil water storage by reducing ET_c, i.e., 0.24–0.37mm d^-1 by straw mulching and 0.05–0.24mm d^-1 by plastic mulching during the trials. Manure application did not affect the ET_c rate and resulted in the highest grain yield (6.8–8.3 Mg ha^˗1) followed by plastic mulching (6.1–8.1 Mg ha^˗1) and straw mulching (5.3–7.5 Mg ha^˗1). Manure application increased the harvest index by optimally allocating biomass because of a steady supply of water and nutrients. The straw mulch, plastic mulch, and manure treatments increased grain yield by 13%, 24%, and 35%, respectively, compared to the control condition. Large-scale implementation of these practices would lessen blue water scarcity in agriculture.

Soil moisture scarcity and soil fertility decline in the drylands contribute to declining crop productivity. The possible synergistic effects of integrating soil & water conservation, and soil fertility management practices on soil moisture, and hence water use efficiency (WUE) in the drylands of Tharaka-Nithi County in Kenya was assessed. The experiment was laid in a three by three split plot arrangement, with four replications, for four cropping seasons. Minimum tillage with mulch, tied ridges, and conventional tillage formed the main plot factors. The sub-plot factors included animal manure plus fertilizer at 120, 60, and 30Nkgha⁻¹. There was significant improvement in soil moisture by 35 and 28% by minimum tillage with mulch and tied ridges, respectively, compared to conventional tillage. Manure plus fertilizer rates of 120 and 60Nkgha⁻¹ had significantly lower soil moisture by 12 and 10%, respectively than the 30Nkgha⁻¹ across the seasons. The WUE was significantly enhanced by 150 and 65% under minimum tillage with mulch and tied ridges, respectively, compared to conventional tillage. Compared with 30Nkgha⁻¹, the 120Nkgha⁻¹ and 60kgha⁻¹ significantly enhanced the WUE by 66 and 25%, respectively. Across the seasons, the best treatment combination for improving WUE was minimum tillage with mulch at 120Nkgha⁻¹ rate of manure plus fertilizer.

Plastic film and gravel mulching in combination with fertilization are widely used to increase crop yields and water productivity (WP) in arid and semiarid areas, but soil surface mulching may stimulate soil organic carbon (SOC) mineralization; therefore, film mulching with manure amendment was proposed to improve soil fertility. However, the combined effects of these practices on yield, WP, and the stocks of SOC and total nitrogen (TN) need to be better understood. This study investigated the long-term effects of different practices on crop yields, WP, and SOC and TN stocks in the 0–20, 20–40 and 40–60cm layers based on a 12-year spring maize (Zea mays L.) field experiment on the Loess Plateau. The treatments included no mulching +NPK (CK), gravel mulching +NPK (GM), film mulching +NPK (FM), and film mulching +NPK +cow manure (FCM). In 2019 and 2020, compared with the control, both FM and FCM significantly increased crop yields, WP, N uptake efficiency (NupE) and N fertilizer productivity (NfP). Compared with CK, the FCM treatment significantly increased the SOC and TN stocks by 44.10% and 39.51%, respectively, on average, and the minimum C input that could maintain the soil C balance on the Loess Plateau was 0.67 Mg ha⁻¹ yr⁻¹. Over the 12 experimental years, compared with the initial value in 2009, the trends of SOC and TN contents in the FM treatment were downward, while those in the FCM treatment increased by 41.61% and 30.27%, respectively, but yearly input of manure led to SOC equilibrium. Compared with CK, the FCM treatment significantly decreased SOC and TN sequestration potential by 33.38% and 19.59%, respectively, on average in topsoil (0–20cm), but it had less of an effect on SOC and TN sequestration at 20–40 and 40–60cm soil depths. The reasons for SOC reaching equilibrium in the FCM treatment were analyzed, and periodic subsoiling was proposed to break the equilibrium state to further improve the sequestration amount of SOC and TN at 0–60cm soil depths. In conclusion, film mulching with manure amendment was recommended as a long-term strategy to improve soil productivity and soil fertility in semiarid farmland.