Rational trade-offs between yield increase and fertilizer inputs are essential for sustainable intensification: A case study in wheat-maize cropping systems in China

Short-term high-temperature pretreated compost increases its application value by altering key bacteria phenotypes

Short-term high-temperature pretreatment can effectively shorten the maturity period of organic waste composting and improve the fertilizer efficiency and humification degree of products. To investigate the effect and mechanism of the end products on the saline-alkali soil improvement and plant growth, the short-term high-temperature pretreatment composting (SHC) and traditional composting (STC) were separately blended with saline-alkali soil in a ratio of 0-40 % to establish a soil-fertilizer blended matrix for cultivating Lolium perenne L. The pot experiments combined with principal component analysis showed Lolium perenne L. planted in 20 % SHC-blended saline-alkali soil had the best growth effect, and its biomass, chlorophyll content, and plant height were 109-113 % higher than STC. The soil physicochemical property analysis showed that SHC and STC increased the soil nutrient content, humification degree, and enzyme activity at any blending ratio. The microbial analysis showed that 20 % SHC in the saline-alkali soil stimulated the growth of functional microorganisms and the addition of SHC promoted the sulfur cycle, nitrogen fixation, and carbon metabolism in the soil-plant system. The correlation analysis showed that pH; nutrient contents; and urease, catalase, sucrase, and phosphatase activities in the saline-alkali soil were significantly correlated with plant growth indexes (p < 0.05). Georgenia and norank_f__Fodinicurvataceae had a stronger correlation with four types of enzyme activities (p < 0.01). SHC improved the saline-alkali soil and promoted plant growth by adjusting soil pH, increasing soil nutrients, and influencing soil enzyme activity and dominant flora. This study provides a theoretical basis for applying SHC products in soil improvement.

Applications of land surface model to economic and environmental-friendly optimization of nitrogen fertilization and irrigation

Land surface models (LSMs) have prominent advantages for exploring the best agricultural practices in terms of both economic and environmental benefits with regard to different climate scenarios. However, their applications to optimizing fertilization and irrigation have not been well discussed because of their relatively underdeveloped crop modules. We used a CLM5-Crop LSM to optimize fertilization and irrigation schedules that follow actual agricultural practices for the cultivation of maize and wheat, as well as to explore the most economic and environmental-friendly inputs of nitrogen fertilizer and irrigation (FI), in the North China Plain (NCP), which is a typical intensive farming area. The model used the indicators of crop yield, farm gross margin (FGM), nitrogen use efficiency (NUE), water use efficiency (WUE), and soil nitrogen leaching. The results showed that the total optimal FI inputs of FGM were the highest (230 ± 75.8 kg N ha-1 and 20 ± 44.7 mm for maize; 137.5 ± 25 kg N ha-1 and 362.5 ± 47.9 mm for wheat), followed by the FIs of yield, NUE, WUE, and soil nitrogen leaching. After multi-objective optimization, the optimal FIs were 230 ± 75.8 kg N ha-1 and 20 ± 44.7 mm for maize, and 137.5 ± 25 kg N ha-1 and 387.5 ± 85.4 mm for wheat. By comparing our model-based diagnostic results with the actual inputs of FIs in the NCP, we found excessive usage of nitrogen fertilizer and irrigation during the current cultivation period of maize and wheat. The scientific collocation of fertilizer and water resources should be seriously considered for economic and environmental benefits. Overall, the optimized inputs of the FIs were in reasonable ranges, as postulated by previous studies. This result hints at the potential applications of LSMs for guiding sustainable agricultural development.

Projecting global fertilizer consumption under shared socioeconomic pathway (SSP) scenarios using an approach of ensemble machine learning

Comprehensively projecting global fertilizer consumption is essential for providing critical datasets in related fields such as earth system simulation, the fertilizer industry, and agricultural sciences. However, since previous studies have not fully considered the socioeconomic factors affecting fertilizer consumption, huge uncertainties may remain in fertilizer consumption projections. Here, an approach ensembled six machine learning algorithms was proposed in this study to predict global fertilizer consumption from 2020 to 2100 by considering the impact of socioeconomic factors under shared socioeconomic pathway (SSP) scenarios. It indicates that the proposed approach provides a rational and reliable framework for fertilizer consumption prediction that stably outperforms the single algorithms with relatively high accuracy (Nash-Sutcliffe efficiency of 0.93, Kling-Gupta efficiency of 0.89, and mean absolute percentage error of 10.97 %). We found that global N and P fertilizer consumption may decrease from 2020 to 2100, while K fertilizer may buck the trend. N fertilizer consumption showed a declining trend of -1 %, -17.13 %, and -3.43 % under the SSP1, SSP2, and SSP3 scenarios in 2100, respectively. For P fertilizer, those were -0.68 %, -9.68 %, and -2.03 %. In contrast, global K fertilizer consumption may increase by 18.03 %, 9.18 %, and 6.74 %, respectively. On average, N, P, and K fertilizer consumption is highest in China, and the lowest is in Kazakhstan. However, the hotspots of N fertilizer consumption may shift from China to Latin America and the Caribbean. This study highlighted the ensemble machine learning approach could potentially be a robust method for predicting future fertilizer consumption. Our prediction product will not only contribute to a better understanding of global fertilizer consumption trends and dynamics but also provide flexible and accurate key data/parameters for related research. The Projected Global Fertilizers Consumption Datasets are available at doi:https://doi.org/10.5281/zenodo.8195593 (Gao et al., 2023).

Soil chemistry, metabarcoding, and metabolome analyses reveal that a sugarcane-Dictyophora indusiata intercropping system can enhance soil health by reducing soil nitrogen loss

Introduction

Greater amounts of fertilizer are applied every year to meet the growing demand for food. Sugarcane is one of the important food sources for human beings.

Methods

Here, we evaluated the effects of a sugarcane-Dictyophora indusiata (DI) intercropping system on soil health by conducting an experiment with three different treatments: (1) bagasse application (BAS process), (2) bagasse + DI (DIS process), and (3) the control (CK). We then analyzed soil chemistry, the diversity of soil bacteria and fungi, and the composition of metabolites to clarify the mechanism underlying the effects of this intercropping system on soil properties.

Results and discussion

Soil chemistry analyses revealed that the content of several soil nutrients such as nitrogen (N) and phosphorus (P) was higher in the BAS process than in the CK. In the DIS process, a large amount of soil P was consumed by DI. At the same time, the urease activity was inhibited, thus slowing down the loss of soil in the DI process, while the activity of other enzymes such as β-glucosidase and laccase was increased. It was also noticed that the content of lanthanum and calcium was higher in the BAS process than in the other treatments, and DI did not significantly alter the concentrations of these soil metal ions. Bacterial diversity was higher in the BAS process than in the other treatments, and fungal diversity was lower in the DIS process than in the other treatments. The soil metabolome analysis revealed that the abundance of carbohydrate metabolites was significantly lower in the BAS process than in the CK and the DIS process. The abundance of D(+)-talose was correlated with the content of soil nutrients. Path analysis revealed that the content of soil nutrients in the DIS process was mainly affected by fungi, bacteria, the soil metabolome, and soil enzyme activity. Our findings indicate that the sugarcane-DIS intercropping system can enhance soil health.

Climatic threshold of crop production and climate change adaptation: A case of winter wheat production in China

Global climate change has adversely affected agricultural production. Identifying the climatic threshold is critical to judge the impact and risk of climate change and proactively adapt agriculture. However, the climatic threshold of agriculture, especially crop production, remains unclear. To bridge this gap, taking winter wheat production from 1978 to 2017 in China as an example, this study clarified the definition of the climatic threshold of crop production and calculated it based on a mechanism model considering multiple factors and their synergies. The results showed that (1) the climate presented a warmer and wetter trend from 1978 to 2017, especially after 1996. (2) Water, fertilizer, and winter wheat yields increased significantly (22.4 mm/decade, 96.4 kg/ha·decade, and 674.2 kg/ha·decade, respectively, p &lt; 0.01). (3) The average optimal temperature and water thresholds for winter wheat were 7.3°C and 569 mm, respectively. The temperature rise was unfavorable for winter wheat production, and the water supply increase was beneficial to winter wheat production. (4) Increasing irrigation and fertilization could raise the optimal temperature threshold and adapt to climate warming in most provinces, while Shandong and Shaanxi both needed to reduce fertilization. We established a generalized method for calculating the climatic threshold of agricultural production and found that multifactor synergistic effects could influence the climatic threshold. The climatic threshold of winter wheat changed with different adaptation levels. However, considering the limitations in resource availability and environmental capacity, increasing the use efficiency of water and fertilizer is more important for adapting to climate change in the future.

Seeking sustainable pathway of crop production by optimizing planting structures and management practices from the perspective of water footprint

Water shortage threatens sustainable agriculture and food security globally. The Huanghuaihai Plain plays a critical role in ensuring China's food security, but at the expense of groundwater quantity and quality. Approaches that integrate crop production and environmental goals offer promise for achieving more sustainable water management in agriculture, yet little work has been done to link potential solutions with planting structure and resource management. The spatiotemporal variation of water footprint, water scarcity footprint, and green water occupancy rate for seven major crops, and the sustainability index and reduction potential of ten targeted reduction scenarios across 486 counties were quantitatively assessed in the Huanghuaihai Plain during 1985-2015. Total and gray water footprints dramatically increased by 59.5 % and 446.8 % from 1985 to 2015, respectively. The water scarcity footprint increased from 43.3 × 10⁹ to 49.9 × 10⁹ m³ and green water occupancy rate decreased from 37.8 % to 36.1 %. Among the single measures, reducing nitrogen input or its leaching would have the optimal reduction potential in WF_total (reduced by 5.5-11.0 %), while adjusting planting structure would have the best sustainable performance. More importantly, the areas with the greatest reduction potential in blue water footprint by deficit irrigation and adjusting planting structure were located in the southeastern and middle parts of the plain, respectively, suggesting that differentiated strategies are required for regional water sustainability. The findings provide not only integrated approaches to inform targeted water management decision making in the Huanghuaihai Plain, but also best practices that may be applicable to other regions facing similar resource concerns.

Metabarcoding and Metabolome Analyses Reveal Mechanisms of Leymus chinensis Growth Promotion by Fairy Ring of Leucocalocybe mongolica

Fairy rings are a unique ecological phenomenon caused by the growth of the fungal mycelium in the soil. Fairy rings formed by Leucocalocybe mongolica (LM) are generally distributed in the Mongolian Plateau, where they promote plant growth without fertilization and alleviate fertilizer use. We previously investigated the soil factors regulating growth promotion in a fairy ring ecosystem; however, the aspects of the plant (Leymus chinensis, LC) that promote growth have not been explored. Therefore, the present study investigated the endophyte diversity and metabolome of LC in an LM fairy ring ecosystem. We analyzed the leaf and root samples of LC from the DARK (FR) and OUT (CK) zones. The fairy rings significantly improved the fungal diversity of roots and leaves and the bacterial diversity of leaves in the FR zone. Ralstonia was the dominant bacteria detected in the LC leaves. In addition, Marasmius, another fairy ring fungal genus, was also detected with a high abundance in the roots of the FR zone. Furthermore, widely targeted metabolome analysis combined with KEGG annotation identified 1011 novel metabolites from the leaves and roots of LC and seven pathways significantly regulated by the fairy ring in the FR zone. The fairy ring ecosystem significantly downregulated the flavonoid metabolism in the leaves and roots of LC. The correlation analysis found Ralstonia is a potential regulatory factor of flavonoid biosynthesis in LC. In addition, salicylic acid and jasmonic acid were found upregulated in the leaves, probably related to Marasmius enrichment. Thus, the study details plant factors associated with enhanced growth in an LM fairy ring ecosystem. These findings lay a theoretical foundation for developing the fairy ring ecosystem in an agricultural system.

Soil Chemical Properties, Metabolome, and Metabarcoding Give the New Insights into the Soil Transforming Process of Fairy Ring Fungi Leucocalocybe mongolica

A unique ecological landscape distributed in the Mongolian Plateau, called fairy rings, caused by the growth of the fungus Leucocalocybe mongolica (LM) in the soil could promote plant growth without fertilization. Therefore, this landscape can alleviate fertilizer use and has excellent value for agricultural production. The previous studies only investigated several parameters of the fairy rings, such as soil microbial diversity and some soil chemical properties, thus conclusions based on the studies on fairy rings lack comprehension. Therefore, the present study systematically investigated the chemical properties, metabolome, and metabarcoding of LM-transformed soil. We analyzed fairy ring soils from DARK (FR) and OUT (CK) zone correlated growth promotion with ten soil chemical properties, including N, nitrate-N, inorganic-P, cellulose, available boron, available sulfur, Fe, Mn, Zn, and Cu, which were identified as important markers to screen fairy ring landscapes. Metabolomics showed that the accumulation of 17 carbohydrate-dominated metabolites was closely associated with plant growth promotion. Finally, metabarcoding detected fungi as the main components affecting soil conversion. Among the various fungi at the family level, Lasiosphaeriaceae, unidentified_Auriculariales_sp, and Herpotrichiellaceae were markers to screen fairy ring. Our study is novel and systematically reveals the fairy ring soil ecology and lists the key factors promoting plant growth. These findings lay a theoretical foundation for developing the fairy ring landscape in an agricultural system.

Integrated Carbon Footprint and Economic Performance of Five Types of Dominant Cropping Systems in China’s Semiarid Zone

Crop production requires large areas of land and makes an important contribution to greenhouse gas emissions. Cleaner production of all crop types could be of great significance to realizing carbon neutrality as soon as possible. The present study adopted life cycle assessment (LCA) combined with the profit accounting method of input-output to compare the differences in greenhouse gas emissions in the entire life cycle of apple (Malus pumila Mill.), grain maize (Zea mays L.), wheat (Triticum aestivum L.), silage maize (Zea mays L.), and alfalfa (Medicago sativa Linn.) production in eastern Gansu Province with three functional units, including per ha of land, per ton of product, and per 10,000 yuan of output value. The results showed that apple had the largest carbon footprint per ha. Wheat had the largest carbon footprint per ton of product and per 10,000 yuan output. The results of LCA inventory sensitivity analysis showed that the main sources of greenhouse gas emissions for all crops were the production process of agricultural materials such as chemical fertilizer, machinery, and agricultural film. In particular, the excessive input of chemical fertilizer was the driving factor resulting in greenhouse gas emissions. Based on the study results, this paper also puts forward certain suggestions on the future land use of the cropping systems in the study area.

Grain Yield Performance and Quality Characteristics of Waxy and Non-Waxy Winter Wheat Cultivars under High and Low-Input Farming Systems

Waxy starch with a modified amylose-to-amylopectin ratio is desired for a range of applications in food and non-food industries; however, yield performance and grain quality characteristics of waxy wheat cultivars are usually inferior in comparison to advanced non-waxy cultivars. In this study, we compared waxy (‘Eldija’, ‘Sarta’) and non-waxy (‘Skagen’, ‘Suleva DS’) winter wheat cultivars grown under high and low-input farming systems over two cropping seasons by evaluating their yield and grain quality, including flour, dough, and starch physicochemical properties. The yield of waxy cv. ‘Sarta’ was significantly lower compared to the non-waxy cultivars across all trials; however, waxy cv. ‘Eldija’ had a similar yield as non-waxy cultivars (except under high-input conditions cv. ‘Skagen’). Moreover, no significant differences were observed between protein and gluten content of waxy and non-waxy cultivars. Low amylose content typical for waxy wheat cultivars highly correlated (r ≥ 0.8) with lower falling number, flour yield and sedimentation values, lower nitrogen % used for grain, higher flour water absorption and flour particle size index. In general, properties dependent on starch structure demonstrated consistent and significant differences between both starch types. The prevailing heat waves during the grain filling period decreased grain test weight but increased protein and gluten content and caused gluten to be weaker. Dough development time at these conditions became longer, dough softening lowered and starch content decreased, but A-starch, starch peak and final viscosity values increased. Low-input farming had a negative effect on grain yield, grain nitrogen uptake and grain test weight but increased phosphorus content in grain. The unique dough mixing properties of waxy cultivar ‘Eldija’ suggest that it could be used in mixtures along with non-waxy wheat for dough quality improvement.

Does agricultural cooperative membership help reduce the overuse of chemical fertilizers and pesticides? Evidence from rural China

The overuse of chemical fertilizers and pesticides (CFPs) has negatively impacted the environment and human health. It is an urgent issue that should be addressed. In this study, we investigate whether agricultural cooperatives can serve as an institutional arrangement that helps reduce the consumption of CFPs, using the data of 2012 family farms from the Ministry of Agriculture and Rural Affairs of China. Various approaches, including instrumental variable-based two-stage residual inclusion approach (2SRI), endogenous switching probit (ESP) model, and endogenous switching regression (ESR) model, are utilized to help address the endogeneity issues of the cooperative membership variable. The results show that agricultural cooperative membership significantly increases the probability of reducing fertilizers and pesticides of the family farms and improves net return per yuan CFPs. The further analysis shows that agricultural cooperative production services reduced the usage of fertilizers and pesticides, while cooperatives marketing services only significantly lowered the use of pesticides. Our findings highlight the importance of promoting the development of agricultural cooperatives to support green agricultural production in China.

Evaluation of coastal farming under salinization and optimized fertilization strategies in China

Nitrogen (N) application and salinity are key factors influencing crop yield and net economic benefit in coastal saline-alkali soils. Integrated analysis and optimization of the benefits of wheat-corn cropping under different nitrogen applications in saline soils could provide lay the scientific basis for sustainable development of agriculture in coastal farmlands. A total of 571 pair-reviewed literature data on two-factor cross-over trials, involving soil salinity and nitrogen application, were integratively analyzed. Based on multi-objective optimization of crop yield, agronomic and net economic benefits, and soil nitrate residue in coastal saline-alkali soils, area-specific nitrogen application strategies were developed. The results showed that increasing the N application rate under 1.8-2.9‰ salinity can increase crop yield and economic benefits. The net economic benefit of crops was negative under 3.5‰ salinity. Above that threshold of 3.5‰, it is not suitable for planting food crops. Consequently, it is necessary to strengthen the management of saline-alkali soils. While the application rate of 2.78 × 10⁸ kg N in winter wheat/summer corn cropping ensured environmental protection, farmers preferred 3.08 × 10⁸ kg of nitrogen dose. These were respectively 40.4% and 33.9% lower than the traditional dose and with relatively higher benefits too.

Effects of water and nitrogen coupling on the photosynthetic characteristics, yield, and quality of Isatis indigotica

Isatis indigotica is a commercial medicinal crop that is widely cultivated with high water and nutrient application, in the arid areas of northwest China. Rational irrigation and nitrogen application are key factors for successful crop management. The objective of this study was to determine the effect of water and nitrogen coupling on the photosynthetic characteristics, yield, and quality of Isatis indigotica produced in northwestern China. Field trials were conducted for 2 consecutive years at an irrigation test station. Data on photosynthetic parameters, yield, and quality were collected from individual Isatis indigotica for each treatment during 2018–2019. The application of nitrogen significantly increased photosynthetic rates and yield under the same irrigation conditions. However, the yields were reduced in the excess water treatments (W3N1 and W3N2) and in the excess nitrogen treatments (W1N3, W2N3, and W3N3) in contrast to the optimum W2N2 treatment. Moreover, the quality indicators of the W2N2 treatment decreased compared with CK, which was due to water stress and more photoassimilates being available to the roots, but the effective quality index value could be effectively improved by greatly increasing the yield.

Role of bioengineering and laborers in integration of farmland resources toward to improve dimension of sustainable agriculture in China

Farmland transfer is one of the essential approaches for achieving large-scale farming and its management affects productive efficiency, environment pollution and food sustainable security supply. Present study was carried out investigation based representative agricultural development area Guanzhong Plain of Shaanxi, aimed at explore the role of biotechnology and laborers in integration of farmland toward to improve sustainable agriculture in rural China by employed the profit and Tobit models evaluation. The conclusion demonstrated that labor’s and agricultural management model as main stay, intensive farming has positive effect-based economic and environmental benefits than fragmentation management, female laborers have weaker effect on farmland renting-out behavior among smallholders while male laborers were superior promoters in increasing the area of rented-in farmland and farm scale. Finally, bioengineering development and agricultural intensification management as a rational choice that has great potential value for large-scale cultivation that contributing a promising future for achieving cleaner production, environment and human health further providing huge economic and social and environmental benefits in sustainability agriculture. Additionally, government policies require intensive intervention to accelerate large-scale management and biotechnology implementation.

Abbreviation: Aaflf: Average age of female labor force; Incom(log): Log of annual household income; Noflf: Number of women in the labor force; Nooaf: Number of old adults in family; NTFs: non-transfer families; OLS: ordinary least square; Palff: Proportion of agricultural laborers in the female labor force; Palmf: Proportion of agricultural laborers in the male labor force; RIFs: rented-in families; ROFs: rented-out families; Whhf: Whether the household head is female

Improving smallholder farmers' maize yields and economic benefits under sustainable crop intensification in the North China Plain

To meet the food demands of a growing population, the maize production systems deployed by smallholders in China have tended towards extremely intensive planting and excessive use of fertilizers, which have caused serious environmental impacts. This study investigated the balance between the maize yield and nitrogen (N) input in the North China Plain (NCP), which is one of the most important grain-producing region in China. Our study compared yield simulations generated by the DSSAT-CERES-Maize model with actual data from a number of multi-site field experiments and an extensive household surveys encompassing 1671 farmers. The smallholders' maize cultivars, plant population, and amount of N input on the crop yield and how these affects the economic benefits were analyzed. The results showed that the average traditional farming methods' yield was 72% of the attainable yield, which means that farmers have ample room to improve their yields. We also found that the maize yields varied widely between farmers, and that most of them applied excessive amounts of N but failing to achieve an optimal yield due to poor fertilization management techniques. The study found that the economic benefits achieved by the farmers were low, but after deploying high-yield (HY) methods, the yield was increased by 34.9% and the economic benefits by 14.4%. The greenhouse gas (GHG) emissions associated with the traditional farming methods were high and could potentially be reduced by 48.6%. All in all, farmers should be given guidance on how to appropriately increase the plant population, reduce the input of N fertilizer, and optimize farmland management measures, so that China can achieve intensive but sustainable agricultural production at a lower environmental cost. It was concluded that there are still numerous biological and abiotic factors that restrict production increases by smallholders. These factors vary from region to region and require further investigation.

Recessive Transition Mechanism of Arable Land Use Based on the Perspective of Coupling Coordination of Input–Output: A Case Study of 31 Provinces in China

In the rapid process of urbanization in China, arable land resources are faced with dual challenges in terms of quantity and quality. Starting with the change in the coupling coordination relationship between the input and output on arable land, this study applies an evaluation model of the degree of coupling coordination between the input and output (D_CCIO) on arable land and deeply analyzes the recessive transition mechanism and internal differences in arable land use modes in 31 provinces on mainland China. The results show that the total amount and the amount per unit area of the input and output on arable land in China have presented different spatio-temporal trends, along with the mismatched movement of the spatial barycenter. Although the D_CCIO on arable land increases slowly as a whole, 31 provinces show different recessive transition mechanisms of arable land use, which is hidden in the internal changes in the input–output structure. The results of this study highlight the different recessive transition patterns of arable land use in different provinces of China, which points to the outlook for higher technical input, optimized planting structure, and the coordination of human-land relationships.

Effect of Different Rates of Nitrogen Fertilization on Crop Yield, Soil Properties and Leaf Physiological Attributes in Banana Under Subtropical Regions of China

Excessive nitrogen (N) application is widespread in Southern China. The effects of N fertilization on soil properties and crop physiology are poorly understood in tropical red loam soil. We conducted a field experiment to evaluate the effect of nitrogen fertilization rates on physiological attributes (chlorophyll, plant metabolic enzymes, soluble matters) on banana leaves, soil properties (soil enzymes, soil organic matter (SOM), soil available nutrients) as well as banana crop yield in a subtropical region of southern China. The N rates tested were 0 (N₀), 145 (N₁₄₅), 248 (N₂₄₈), 352 (N₃₅₂), 414 (N_FT), and 455 (N₄₅₅) g N per plant. The correlations among soil factors, leaf physiological factors and crop yield were evaluated. The results indiated that the high rates of N fertilization (N_FT and N₄₅₅) significantly decreased soil available potassium (K) content, available phosphorus (P) content, glutamine synthetase (GS) activity, and soluble protein and sugar contents compared with lower N rates. The N₃₅₂ treatment had the highest crop yields compared with higher N rates treatments, followed by the N₄₅₅ treatment. However, there were no significant differences in crop yields among N fertilization treatments. Factor analysis showed that the N₃₅₂ treatment had the highest integrated score for soil and leaf physiological factors among all treatments. Moreover, the N₃₅₂ treatment was the most effective in improving carbon and nitrogen metabolism in banana. Crop yield was significantly and positively linearly correlated with the integrated score (r = 0.823, p < 0.05). Path analysis revealed that invertase, SOM and sucrose synthase (SS) had a strong positive effect on banana yield. Canonical correspondence analysis (CCA) suggested that available K, invertase, acid phosphatase and available P were the most important factors impacting leaf physiological attributes. Cluster analysis demonstrated distinct differences in N application treatment related to variations in soil and leaf factors. This study suggested that excessive N fertilization had a negative effect on soil fertility, crop physiology and yield. The lower N rates were more effective in improving crop yield than higher rates of N fertilization. The N rate of 352 g N per plant (N₃₅₂) was recommended to reduce excess N input while maintaining the higher yield for local farmers' banana planting.

Narrowing Yield Gaps and Enhancing Nitrogen Utilization for Summer Maize (Zea mays L) by Combining the Effects of Varying Nitrogen Fertilizer Input and Planting Density in DSSAT Simulations

In China, the most common grain crop is maize (Zea mays). The increasing pressure to meet the food demands of its growing population has pushed Chinese maize farmers toward an excessive use of chemical fertilizers, a practice which ultimately leads to a massive waste of resources and widespread environmental pollution. As a result, increasing the yield and improving the nitrogen (N) use efficiency of maize has become a critical issue for agriculture in China. This study, which analyzes the combined data from a simulation carried out using the Decision Support System for Agrotechnology Transfer (DSSAT), a field experiment, and a household survey, explored the effectiveness of several approaches aimed at narrowing the maize yield gap and improving the N utilization efficiency in the Huang-Huai-Hai Plain (HHHP), the most important area for the production of summer maize in China. The various approaches we studied deploy different methods for the integrated management of N fertilizer input and the planting density. The study produced the following results: (1) For the simulated and actual maize yields, the root mean square error (RMSE), the normalized root mean squared errors (NRMSE) and the index of agreement (d) were 1,171 (kg ha^-1), 12% and 0.84, respectively. These results show that the model is viable for the experiment included in the study; (2) The potential yield was 15.58 t ha^-1, and the yields achieved by the super-high-yield cultivation pattern (SH), the optimized nutrient and density management pattern (ONM), the simulated farmer's practice cultivation pattern (FP) and actual farmer's practice (AFP) were 11.43, 11.06, 10.33, and 7.95 t ha^-1, respectively. The yield gaps associated with the different yield levels were large; (3) For summer maize, the high yield and a high N partial factor productivity (NPFP) was found when applying a planting density of 9 plants m^-2 and an N application amount of 246 kg ha^-1. These results suggest that the maximum yield that can actually be achieved by optimizing the N application and planting density is less than 73% of the potential yield. This implies in turn that in order to further narrow the observed yield gaps, other factors, such as irrigation, sowing dates and pest control need to be considered.