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Maize plays a vital role in enhancing food security, particularly in regions facing agricultural challenges such as poor soil conditions, erratic rainfall, and limited access to resources. It can be advantageous for smallholder farmers in developing countries, where it can enhance productivity on limited land and under suboptimal soil conditions. One of the potential means for improving crop yield under suboptimal soil conditions, such as acidic soils, is the application of soil amendments. However, the combined effects of functionalized biochar (a pyrogenic carbon) and microbes on phosphorus (P) bioavailability and plant growth performance are still not well understood. This study investigates the optimization of transplanted maize growth in acidic soil through the application of rice husk biochar (RHB) that was oxidized with 10% hydrogen peroxide and inoculated with Pseudomonas aeruginosa, a phosphate-solubilizing bacterium. The oxidized biochar’s pH was adjusted to 6.2 to enhance its effectiveness in challenging soil conditions. Soil properties and maize performance were determined using a pot culture. Results showed that the combined use of 10% oxidized RHB and Pseudomonas aeruginosa significantly increased P availability and phosphatase enzyme activity by 435% and 418%, respectively. Additionally, 10% Oxidized RHB treatment, microbes treatment and combination of biochar and microbes treatment showed yield increment 52%, 51% and 313% respectively, demonstrating the effectiveness of the treatment in improving soil fertility and crop productivity. This improvement in yield might have occurred due to an increase in soil pH, P bioavailability, and a reduction in Al toxicity since there were significant positive relationships between yield and soil pH and available P and a negative relationship with available Al concentration. These findings underscore the potential of integrating oxidized biochar and beneficial microbes, Pseudomonas aeruginosa, to enhance crop performance in acidic soils.

Black soldier fly frass fertilizer (BSFFF) is increasingly gaining momentum worldwide as organic fertilizer. However, research on its performance on crop production remains largely unknown. Here, we evaluate the comparative performance of BSFFF and commercial organic fertilizer (SAFI) on maize (H513) production. Both fertilizers were applied at the rates of 0, 2.5, 5, and 7.5 t ha-1, and 0, 30, 60, and 100 kg nitrogen (N) ha-1. Mineral fertilizer (urea) was also applied at 0, 30, 60 and 100 kg N ha-1 to establish the N fertilizer equivalence (NFE) of the organic fertilizers. Maize grown in plots treated with BSFFF had the tallest plants and highest chlorophyll concentrations. Plots treated with 7.5 t ha-1 of BSFFF had 14% higher grain yields than plots treated with a similar rate of SAFI. There was a 27% and 7% increase in grain yields in plots treated with 100 kg N ha-1 of BSFFF compared to those treated with equivalent rates of SAFI and urea fertilizers, respectively. Application of BSFFF at 7.5 t ha-1 significantly increased N uptake by up to 23% compared to the equivalent rate of SAFI. Likewise, application of BSFFF at 100 kg N ha-1 increased maize N uptake by 76% and 29% compared to SAFI and urea, respectively. Maize treated with BSFFF at 2.5 t ha-1 and 30 kg N ha-1 had higher nitrogen recovery efficiencies compared to equivalent rates of SAFI. The agronomic N use efficiency (AEN) of maize treated with 2.5 t ha-1 of BSFFF was 2.4 times higher than the value achieved using an equivalent rate of SAFI. Also, the AEN of maize grown using 30 kg N ha-1 was 27% and 116% higher than the values obtained using equivalent rates of SAFI and urea fertilizers, respectively. The NFE of BSFFF (108%) was 2.5 times higher than that of SAFI. Application rates of 2.5 t ha-1 and 30 kg N ha-1 of BSFFF were found to be effective in improving maize yield, while double rates of SAFI were required. Our findings demonstrate that BSFFF is a promising and sustainable alternative to commercial fertilizers for increased maize production.

Pre-growing season prediction of crop production outcomes such as grain yields and nitrogen (N) losses can provide insights to farmers and agronomists to make decisions. Simulation crop models can assist in scenario planning, but their use is limited because of data requirements and long runtimes. Thus, there is a need for more computationally expedient approaches to scale up predictions. We evaluated the potential of four machine learning (ML) algorithms (LASSO Regression, Ridge Regression, random forests, Extreme Gradient Boosting, and their ensembles) as meta-models for a cropping systems simulator (APSIM) to inform future decision support tool development. We asked: (1) How well do ML meta-models predict maize yield and N losses using pre-season information? (2) How many data are needed to train ML algorithms to achieve acceptable predictions? (3) Which input data variables are most important for accurate prediction? And (4) do ensembles of ML meta-models improve prediction? The simulated dataset included more than three million data including genotype, environment and management scenarios. XGBoost was the most accurate ML model in predicting yields with a relative mean square error (RRMSE) of 13.5%, and Random forests most accurately predicted N loss at planting time, with a RRMSE of 54%. ML meta-models reasonably reproduced simulated maize yields using the information available at planting, but not N loss. They also differed in their sensitivities to the size of the training dataset. Across all ML models, yield prediction error decreased by 10%-40% as the training dataset increased from 0.5 to 1.8 million data points, whereas N loss prediction error showed no consistent pattern. ML models also differed in their sensitivities to input variables (weather, soil properties, management, initial conditions), thus depending on the data availability researchers may use a different ML model. Modest prediction improvements resulted from ML ensembles. These results can help accelerate progress in coupling simulation models and ML toward developing dynamic decision support tools for pre-season management.

Biochar, as a soil conditioner, has been widely used to promote the growth of maize, but most of the current research is short-term experiments, which limits the research on the long-term effects of biochar, especially the physiological mechanism of biochar on maize growth in aeolian sandy soil is still unclear. Here, we set up two groups of pot experiments, respectively after the new biochar application and one-time biochar application seven years ago (CK: 0 t ha -1 , C1: 15.75 t ha -1 , C2: 31.50 t ha -1 , C3: 63.00 t ha -1 , C4: 126.00 t ha -1 ), and planted with maize. Subsequently, samples were collected at different periods to explore the effect of biochar on maize growth physiology and its after-effect. Results showed that the plant height, biomass, and yield of maize showed the highest rates of increase at the application rate of 31.50 t ha -1 biochar, with 22.22% increase in biomass and 8.46% increase in yield compared with control under the new application treatment. Meanwhile, the plant height and biomass of maize increased gradually with the increase of biochar application under the one-time biochar application seven years ago treatment (increased by 4.13%-14.91% and 13.83%-58.39% compared with control). Interestingly, the changes in SPAD value (leaf greenness), soluble sugar and soluble protein contents in maize leaves corresponded with the trend of maize growth. Conversely, the changes of malondialdehyde (MDA), proline (PRO), catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) manifested an opposite trend to the growth of maize. In conclusion, 31.50 t ha -1 biochar application can promote the growth of maize by inducing changes in its physiological and biochemical characteristics, but excessive biochar application rates ranging from 63.00-126.00 t ha -1 inhibited the growth of maize. After seven years of field aging, the inhibitory effect of 63.00-126.00 t ha -1 biochar amount on maize growth disappeared and changed to promoting effect.

Use of inorganic fertilizers in smallholder cropping systems in Africa is often becoming inefficient due to increasing unresponsiveness to fertilizer application. A study was conducted for 2 years (four seasons) to assess the effects of biochar made from Prosopis juliflora (Sw.) DC. biomass on nutrients, fauna abundance and subsequent influence on maize planted in a nitisol. There were 12 amendments comprising: (i) biochar applied alone at a rate of 5 and 10 Mg ha−1; (ii) three fertilizer types applied separately (di-ammonium phosphate (18:46:0), urea (46:0:0) and composite NPK (23:23:0)); (iii) six fertilizer + biochar blends of the three fertilizer types and two biochar rates (0.05 and 0.1 Mg ha−1); and (iv) a control with no inputs. Treatments were replicated four times in a randomized complete block design. The amendments were applied in the first two seasons, while the last two were used to assess residual effects. At the end of the first two seasons, total C and N were higher in soils where biochar or fertilizer + biochar was applied, with more than 15.0 g C and 1.9 g N kg−1, compared to 10.4 g C and 1.0 g N kg−1 in control plots. Available P and exchangeable K were over 200% and 100% higher in biochar or fertilizer + biochar amended than control soils, respectively. Application of biochar had no effects on macrofauna such as beetles, centipedes, millipedes, termites and ants, but attracted earthworms. Soil that received 10 Mg biochar ha−1 recorded twice the number of earthworms (207 individuals m−2) compared to soil with 5 Mg biochar ha−1 (105 individuals m−2) and control (97 individuals m−2). Soils which received biochar, with or without fertilizer, had higher taxonomic richness (7.0 species) compared to soils which received DAP (2.8) or NPK (3.8). Nematodes, particularly bacterivorous groups, decreased by more than eight times with biochar application. In the first and second seasons, 5.6 Mg maize grain yield ha−1 was obtained from plots amended with biochar (without fertilizer), which was about six times higher than that harvested from unfertilised control at 0.9 Mg ha−1. Yield differences in plots where fertilizer was applied with or without biochar were not significant. Yield in the third and fourth seasons declined to 3.2 and 1.5 Mg ha−1, irrespective of fertilizer type or biochar amounts.

Secondary soil salinization in arid and semi-arid regions is a serious problem that severely hampers local agricultural productivity and poses a threat to the long-term sustainability of food production. the utilization of organic soil amendments presents a promising approach to mitigate yield losses and promote sustainable agricultural production in saline-alkali soil. In this study, we established four distinct treatments, chemical fertilizer (CK), humic acid with chemical fertilizer (HA), carboxymethyl cellulose with chemical fertilizer (CMC), and amino acid with chemical fertilizer (AA), to elucidate their respective impacts on the reclamation of saline soil and the growth of maize. The findings of our study reveal notable variations in desalination rates within the 0-40 cm soil layer due to the application of distinct soil amendments, ranging from 11.66% to 37.17%. Moreover, application of amendments significantly increased the percentage of soil macro-aggregates as compared to the CK treatment. Furthermore, HA and AA treatments significantly augmented soil nutrient content (HA: 48.07%; AA: 39.50%), net photosynthetic rate (HA: 12.68%; AA: 13.94%), intercellular CO 2 concentration (HA: 57.20%; AA: 35.93%) and maize yield (HA:18.32%; AA:16.81%). Correlation analysis and structural equation modeling unveiled diverse mechanisms of yield enhancement for HA, CMC, and AA treatments. HA enhanced yield by increasing organic matter and promoting soil aggregate formation, CMC improved soil water content and facilitated salt leaching due to its excellent water-holding properties, while AA increased yield by elevating soil organic matter and effective nitrogen content. Among the array of soil amendment materials scrutinized, HA treatment emerged as the most promising agent for enhancing soil conditions and is thus recommended as the preferred choice for treating local saline soils.

Climate variability poses serious challenges to productivity and food safety in rain-fed semi-arid areas. A study on the impact of Tmax, Tmin, and precipitation on the yield of maize was performed in Ariyalur and Perambalur districts, Tamil Nadu, using historical data from 1985 to 2020 and future projection data from 2021 to 2100 under the Shared Socioeconomic Pathways-SSP2-4.5 climate change scenario. Climate extremes analysis shows the results that there is an increase in warm nights (TN90P), warm days (TX90p), heavy rainfall events (R10mm, R20mm), and shorter dry spells (CDD), reflecting more heat and extreme rainfall in both districts. Temperature is increasing considerably; Max and Min temperatures are projected to rise by 1.5 to 2°C by 2100. Patterns of precipitation are changing, with more frequent moderate rainfall events of 10-20 mm and fewer dry spells. From Ariyalur, in conditions of a rise in minimum temperature by 1°C, there has been a reduction of up to 38.2% in maize yield, and it explained 20-25% of variability in yield. Perambalur experiences a 21.7% yield reduction per 1°C with less intensity. The model from Ariyalur outperforms the one from Perambalur, adjusted R² being 0.967 and 0.511, respectively, which suggests that local sites have different sensitivities to climate. The findings from the present research signify the urgent need for adaptive strategies, including heat-tolerant varieties of maize, efficient irrigation, and integrated pest management, which could help mitigate climate risks.

Many people in African countries derive their livelihoods from agriculture. Therefore, unfavourable environmental and climatic conditions render them more vulnerable to increasing food insecurity and poverty rates. However, few studies have investigated how farmers’ adaptation strategies affect farm productivity and household food security in the Sahelian region, notably Mali. We analyse factors that influence adaptation strategies to climate change and the impacts of the adaptation strategies on maize productivity and household food security in southern Mali. Farmers use adaptation strategies such as organic fertilizers, changing planting dates and growing of short duration maize varieties to mitigate against the negative effects of climate change. We find that farmer experience, number of livestock owned, off-farm employment, access to credit, farmer association and technical training exert positive effects on the use of planting short-duration maize varieties as an adaptation strategy, while distance to the farm shows a negative effect. We observe that household size, experience in maize farming, number of livestock owned and technical training positively influence farmers to change planting dates as an adaptation strategy. The use of organic fertilizers and short-duration maize varieties promote maize productivity and food security. We conclude that building farmers’ adaptive capacity tends to reduce their vulnerability to climate change by increasing crop yields and food security.

Increasing maize grain yield has been a major focus of both plant breeding and genetic engineering to meet the global demand for food, feed, and industrial uses. We report that increasing and extending expression of a maize MADS-box transcription factor gene, zmm28, under the control of a moderate-constitutive maize promoter, results in maize plants with increased plant growth, photosynthesis capacity, and nitrogen utilization. Molecular and biochemical characterization of zmm28 transgenic plants demonstrated that their enhanced agronomic traits are associated with elevated plant carbon assimilation, nitrogen utilization, and plant growth. Overall, these positive attributes are associated with a significant increase in grain yield relative to wild-type controls that is consistent across years, environments, and elite germplasm backgrounds.

Expanding eco-friendly approaches to improve plant growth and crop productivity is of great important for sustainable agriculture. Therefore, a field experiment was carried out at the Faculty of Agriculture Farm, Mansoura University, Egypt during the 2018 and 2019 growing seasons to study the effects of different bio- and organic fertilizers and their combination on hybrid maize growth, yield, and grain quality. Seeds were treated with Azotobacter chrocoocum, arbuscular mycorrhizal fungi (AMF), Bacillus circulans, biogas slurry, humic acid (HA), and their combination aiming to increase the growth and yield of maize and to reduce the need for chemical fertilizers. The results showed that combined application of the biofertilizer mixture (Azotobacter chrocoocum, AMF, and Bacillus circulans) with organic fertilizers enhanced maize growth, yield, and nutrient uptake. Moreover, the bio-organic fertilization has improved the soluble sugars, starch, carbohydrates, protein, and amino acid contents in maize seeds. Additionally, the bio-organic fertilization caused an obvious increase in the microbial activity by enhancing acid phosphatase and dehydrogenase enzymes, bacterial count, and mycorrhizal colonization levels in maize rhizosphere as compared with the chemical fertilization. Additionally, the bio-organic fertilizers has improved α-amylase and gibberellins (GA) activities and their transcript levels, as well as decreased the abscisic acid (ABA) level in the seeds as compared to the chemical fertilizers. The obtained results of bio-organic fertilization on the growth parameters and yield of maize recommend their use as an alternative tool to reduce chemical fertilizers.