Nitrogen Fertilizer Application Rates Research Articles

Rock Phosphate and Biochar Effects on Greenhouse Gas Emissions and Soil Fertility in Southern Alberta Potato Field

The application of biochar soil amendment and rock phosphate fertilizer to the soil could lead to achieving net zero emissions and food security; however, the effectiveness of using biochar and rock phosphate in southern Alberta brown chernozemic soil is not yet assessed. In the first trial of this study, varying levels of urea (N), with varying levels of biochar (B) were applied. The same level of rock phosphate (RP) and triple super phosphate (TSP) were applied to compare efficiency of the two fertilizers. The second trial involved applying the same nutrients, but with higher levels than the first trial. The results indicated that the fertilizer application rates did not affect the growth and yield of potatoes because of the application rates of the fertilizer and fertility status of the soil, whereas in the second trial, TSP and RP treatments had the same growth and yield. Furthermore, the high application rate of nitrogen fertilizer and RP with or without biochar in the potato plot emitted high nitrous oxide gas emissions while the low application rate of nitrogen fertilizer and RP kept the carbon dioxide in the soil. Nevertheless, in the second experiment, the application of biochar and rock phosphate reduced nitrous oxide and carbon dioxide emissions. We observed high residual nitrogen and manganese nutrients after harvest in the plot treated to rock phosphate and biochar. Therefore, rock phosphate and biochar have the potential to increase food production and mitigate climate change.

Enhancing root physiology for increased yield in water-saving and drought-resistance rice with optimal irrigation and nitrogen

ObjectivesWater-saving and drought-resistance rice (WDR) plays a vital role in the sustainable development of agriculture. Nevertheless, the impacts and processes of water and nitrogen on grain yield in WDR remain unclear.MethodsIn this study, Hanyou 73 (WDR) and Hyou 518 (rice) were used as materials. Three kinds of nitrogen fertilizer application rate (NFAR) were set in the pot experiment, including no NFAR (nitrogen as urea applied at 0 g/pot), medium NFAR (nitrogen as urea applied at 15.6 g/pot), and high NFAR (nitrogen as urea applied at 31.2 g/pot). Two irrigation regimes, continuous flooding cultivation and water stress, were set under each NFAR. The relationships between root and shoot morphophysiology and grain yield in WDR were explored.ResultsThe results demonstrated the following: 1) under the same irrigation regime, the grain yield of two varieties increased with the increase of NFAR. Under the same NFAR, the reduction of irrigation amount significantly reduced the grain yield in Hyou 518 (7.1%–15.1%) but had no substantial influence on the grain yield in Hanyou 73. 2) Under the same irrigation regime, increasing the NFAR could improve the root morphophysiology (root dry weight, root oxidation activity, root bleeding rate, root total absorbing surface area, root active absorbing surface area, and zeatin + zeatin riboside contents in roots) and aboveground physiological indexes (leaf photosynthetic rate, non-structural carbohydrate accumulation in stems, and nitrate reductase activity in leaves) in two varieties. Under the same NFAR, increasing the irrigation amount could significantly increase the above indexes in Hyou 518 (except root dry weight) but has little effect on Hanyou 73. 3) Analysis of correlations revealed that the grain yield of Hyou 518 and Hanyou 73 was basically positively correlated with aboveground physiology and root morphophysiology, respectively.ConclusionThe grain yield could be maintained by water stress under medium NFAR in WDR. The improvement of root morphophysiology is a major factor for high yield under the irrigation regime and NFAR treatments in WDR.

Regulation of photoassimilate transportation and nitrogen uptake to decrease greenhouse gas emissions in ratooning rice with higher economic return by optimized nitrogen supplies

Mechanized harvesting of the main crop rice, with low stubble height in rice ratooning is scaling up, especially in Southeast China with a higher population density and less cultivated land. Currently, the common nitrogen fertilization for ratoon rice is concentrated within 20 days before and after the harvest of the main crop. However, this fertilization pattern may not be suitable for low stubble regenerative rice due to its extended growth period, leading to diminished nitrogen utilization efficiency and heightened greenhouse gas emissions, particularly nitrous oxide (N2O) emissions. It is imperative to explore a nitrogen fertilizer management model for clean production of low stubble ratoon rice (RR). In this study, we examined the effects of nitrogen fertilizer application rates and methods (single or split application) on yield and greenhouse gas emissions during the regrowth season. We employed a multi-criteria assessment approach combined with field measurements, energy analysis, environmental assessment, and economic evaluation on ratoon rice under various nitrogen fertilizer treatments. The results showed that the ratoon rice produced the highest total energy output under 67.5N+22.5N (Fertilize with 67.5kg nitrogen ha-1 and 22.5kg nitrogen ha-1 3 days after main season rice harvesting and during the heading stage of ratoon rice) treatment compared to the 90N+0N (conventional fertilization, apply 90kg nitrogen ha-1 fertilizer 3 days after harvesting at once) treatment. It was also found that reducing nitrogen application during the tillering stage reduced CH4 emissions, fertilization during the heading stage of the ratoon rice did not increase CH4 emissions, Since fertilization during the heading stage of ratoon rice did not lead to an increase in the partitioning of photoassimilates (photosynthetic product assimilates) to the rhizosphere soil, significant differences in sugar and acetic acid levels were not observed in the rhizosphere soil. As a result, no change was found in the expression of the methanogenic mcrA gene in the microbial community. The study also demonstrated that the 67.5N+22.5N treatment was able to promote the absorption of nitrogen nutrients, reduction in N2O emissions by 16.61%, subsequently increasing resource use efficiency, final yield and net ecosystem economic benefit by 5.96%, 7.19% and 5.57%, respectively, thereby decreasing carbon and nitrogen footprints by 6.64% and 3.50% compared with the 90N+0N treatment in the ratoon rice. These results suggest that a reasonable ratoon rice cultivation scheme is a promising farming system that can simultaneously improve resource use efficiency and economic profits, reduce greenhouse gas emissions and environmental footprint, while still maintaining the high productivity in ratoon rice.

Determining the Profitability of Different NPSB and Nitrogen Fertilizer Rates on Yield and Yield Attributes of SweetPotato (Ipomoea batatas L.) in the Midland Areas of Guji Southern Oromia, Ethiopia

Sweet potato is a crucial crop for food security and income generation. Sweet potato vine length, number of stems, average number of roots per plant, average root weight, marketable root yield, non-marketable root yield, and total sweet potato root yield were determined by the NPSB and nitrogen fertilizer application rates (p<0.01). Using the right fertilizer recommendations can improve crop growth and yield while minimizing resource use. Both NPSB and Nitrogen fertilizer rates had a highly significant impact on root number, root weight, marketable root yield, unmarketable root yield, and total root yield. The combination of 100 kg ha-1 NPSB fertilizer and 69 kg ha-1 of Nitrogen fertilizer gave the highest marketable root yield (553.09 qt ha-1). The treatment with 100 kg ha-1 NPSB fertilizer and 46 kg ha-1 Nitrogen fertilizer demonstrated the best result in terms of marginal rate of returns, with a marginal revenue of 17872%. To optimize sweet potato productivity in the Adola rede region, it is recommended to apply 100 kg ha-1 NPSB and 46 kg ha-1 nitrogen fertilizer. In general, cultivation in the Adola rede region can be optimized by applying a combination of 100 kg ha-1 of NPSB fertilizer and 46 kg ha-1 of nitrogen, resulting in improved plant growth and marketability, higher root yields and cost efficiency.

Effect of Nitrogen Management Strategies on Yield, Quality and Nitrogen Uptake by Wheat (Triticum aestivum L.)

There is little knowledge among farmers on the rate of nitrogen-fertilizer application. Therefore, there is a need to determine optimal rate of nitrogen-fertilizer application on growth and yield of wheat. Accordingly, an field experiment was conducted during the winter (Rabi) season at Crop Research Centre the Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut, Uttar Pradesh, to study the impact of different nitrogen level and splitting modules on quality, yield and nitrogen uptake by wheat (Triticum aestivum L.) crop. The main object of investigation was to find out the optimum dose and splitting of nitrogen for wheat in irrigated system under integrated nitrogen management approach. The experiment consisting of four nitrogen levels viz. control i.e. 0 kg N ha-1 , 90 kg N ha-1, i.e 120 kg N ha-1 and 150 kg N ha-1 as main plots and four splitting modules M1- 50% N as basal through VC, + 25% at CRI + 25% booting stage through urea, M2-50 % N as basal through FYM + 25% at tillering + 25% at booting stage through urea, M3 -50% N as basal through VC+FYM (1:1), + 25% at tillering + 20% at booting stage and 5 % N as foliar spray at pre flowering stage through urea, M4 -50% N as basal through VC+FYM (1:1), rest based on SPAD reading through urea as sub-plots. The experimental results revealed that the plot which fertilized with 150 kg N ha-1 gave higher yield-attributing characters and yield (grain, straw and biological yield). The application of 150 kg N ha-1 resulted in 0.44, 15.25 and 80.8 per cent during 2016-17 and 0.41, 13.05 and 79.2 per cent during 2017-18 produced the higher grain yield over 120, 90 and 0 kg N ha-1. The content and uptake of nitrogen by grain, straw and total uptake as well as protein content and protein yield were obtained with 150 Kg N ha-1 but differences between 120 and 150 kg N ha-1 were non-significant, during both the year 2016-17 and 2017-18. Among different splitting modules M3 resulted significantly higher entire yield attributes, yield (grain and straw yield), nitrogen content and uptake by grain, straw and total uptake as well as content and yield of protein. The M3 module produced higher grain yield by 7.9, 14.7 and 24.8 per cent during 2016-17 and 8.1, 14.89 and 25.2 per cent during 2017-18 over M4, M1 and M2 splitting modules, respectively.

The implementation of the SPAD-502 Chlorophyll meter for the quantification of nitrogen content in Arabica coffee leaves

The utilization of a non-destructive SPAD-502 chlorophyll meter, which enables the measurement of nitrogen status in plant leaves, has gained popularity in agronomic crops. Its application to horticultural crops like coffee remains relatively uncommon. The device provides quick and real-time measurements, helping to provide on-time nitrogen fertilizer to coffee plants before deficiency signs occur. Coffee leaves are characterized by thick and waxy leaves, together with many layers of tree crown. Therefore, the objective of this study was to develop a method for measuring nitrogen levels in coffee plants using the SPAD-502 Chlorophyll meter for an appropriate nitrogen fertilizer application rate in Arabica coffee plants.• Coffee trees were separated into upper, middle and lower levels. Data on SPAD values and total nitrogen were analyzed.• Pearson Correlation Coefficient (R), Coefficient of Determination (R2) and linear regression were calculated for different three levels of both SPAD-502 and total nitrogen values.• The results revealed a strong correlation (R2 = 0.63) between the SPAD readings of coffee leaves obtained from the upper canopy and their nitrogen content.These findings can provide a good concept of which coffee crown level will be a better part for measuring N content using a SPAD-502 Chlorophyll meter.

Integrated straw-derived biochar utilization to increase net ecosystem carbon budget and economic benefit and reduce the environmental footprint

ContextCrop residues are often returned to the soil to achieve soil carbon (C) sequestration in the agricultural sector, thereby mitigating climate change and soil degradation. However, direct straw incorporation may increase the risks of greenhouse gas (GHG) and reactive nitrogen (Nr) emissions. Objective and methodsTo comprehensively evaluate whether straw-derived biochar is a feasible alternative to straw for increasing grain yields and soil C sequestration while reducing GHG and Nr emissions in cropland, we conducted a two-factor field trial on maize farmland in northwest China during 2019–2021. Factor one comprised three straw incorporation methods (straw removal (T), total straw incorporation (S), and straw-derived biochar incorporation (B; biochar application at a straw/biochar ratio of 33%)) and factor two comprised two nitrogen (N) fertilizer application rates (0 and 300 kg ha–1). The relative benefits of the treatments for the maize productivity, net ecosystem carbon budget (NECB), carbon footprint (CF), nitrogen footprint (NF), and net ecosystem economic benefits (NEEB) were comprehensively evaluated by using the life cycle assessment (LCA) and Z-score methods. ResultsN fertilizer application was the main factor that increased maize productivity, NECB, NF, and NEEB in the maize agroecosystem. Under conventional N application, NECB increased by 244.0% (1647.37 kg C ha–1 yr–1) under SN compared with TN, and heterotrophic respiration (Rh) and N2O emissions increased by 70.3% and 34.9%, respectively. By contrast, BN increased NECB by 295.8% (1996.79 kg C ha–1 yr–1), and decreased Rh and N2O emissions by 8.2% and 20.9%, respectively. Hence, BN reduced the net global warming potential (NGWP) and greenhouse gas intensity (GHGI) of the farmland ecosystems by 56.4% (1609.49 kg CO2-eq ha–1 yr–1) and 46.5%, respectively, compared with SN. Moreover, the grain yield, water use efficiency (WUE) and N use efficiency increased significantly under BN compared with TN. Compared to SN, integrated straw-derived biochar utilization (pre-farm abatement + BN management on the farm) reduced the average CF and NF of the maize agroecosystem by 350.2% (4004.85 kg CO2-eq ha–1 yr–1) and 16.5% (12.68 kg N-eq ha–1 yr–1), respectively, and improved NEEB by $ 624.7 ha–1 yr–1. ConclusionsIntegrated straw-derived biochar utilization may be applied as a sustainable and economical straw alternative to straw for enhancing soil C sinks and reducing GHG and Nr emissions. Implications or significanceIntegrated straw-derived biochar utilization is an economically friendly and sustainable method for straw utilization in dryland maize production, and highly significant for mitigating climate and environmental degradation.

Genome-wide association study of agronomic traits related to nitrogen use efficiency in Henan wheat

BackgroundNitrogen use efficiency (NUE) is closely related to crop yield and nitrogen fertilizer application rate. Although NUE is susceptible to environments, quantitative trait nucleotides (QTNs) for NUE in wheat germplasm populations have been rarely reported in genome-wide associated study.ResultsIn this study, 244 wheat accessions were phenotyped by three NUE-related traits in three environments and genotyped by 203,224 SNPs. All the phenotypes for each trait were used to associate with all the genotypes of these SNP markers for identifying QTNs and QTN-by-environment interactions via 3VmrMLM. Among 279 QTNs and one QTN-by-environment interaction for low nitrogen tolerance, 33 were stably identified, especially, one large QTN (r2 > 10%), qPHR3A.2, was newly identified for plant height ratio in one environment and multi-environment joint analysis. Among 52 genes around qPHR3A.2, four genes (TraesCS3A01G101900, TraesCS3A01G102200, TraesCS3A01G104100, and TraesCS3A01G105400) were found to be differentially expressed in low-nitrogen-tolerant wheat genotypes, while TaCLH2 (TraesCS3A01G101900) was putatively involved in porphyrin metabolism in KEGG enrichment analyses.ConclusionsThis study identified valuable candidate gene for low-N-tolerant wheat breeding and provides new insights into the genetic basis of low N tolerance in wheat.

Optimizing Phosphorus Fertilizer Use on the Loess Plateau: Impact on Soil Properties and Crop Production Efficiency

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.

Trade‐off between soil carbon sequestration and net ecosystem economic benefits for paddy fields under long‐term application of biochar

AbstractThe application of biochar and nitrogen fertilizer can increase rice yield, soil organic carbon (SOC) storage and reduce greenhouse gas (GHG) emissions. However, few studies have systematically evaluated the carbon footprint (CF) and net ecosystem economic benefits (NEEB) of paddy ecosystems under long‐term application of biochar and nitrogen fertilizer. Here, the life cycle assessment method was used to quantify the CF and NEEB of paddy fields under different biochar and nitrogen fertilizer application rates in 7 years. Three biochar rates of 0 (B0), 4.5 (B1) and 13.5 t ha−1 year−1 (B2) and two nitrogen fertilizer rates of 0 (N0) and 300 kg ha−1 year−1 (N) were set. The results showed that B2 significantly increased methane (CH4) emission by 38%, decreased nitrous oxide (N2O) emission by 29%, and significantly increased global warming potential by 27% compared with B0. Besides that, biochar application significantly increased ΔCSOC by 87%–173% and reduced CF by 1.6–1.8 Mg CO2 eq ha−1. Among them, CH4 and N2O emissions contributed 46%–95% of total GHG emissions, and the production and transportation of nitrogen fertilizer and biochar contributed 17%–52% of total GHG emissions. Nitrogen fertilizer application can significantly increase rice yield by 85% compared to the N0, which could bring the largest NEEB. Biochar application had a negative influence on the NEEB regardless of N application. This might be attributable to the fact that the economic gains from increased rice production and SOC caused by biochar cannot outweigh the high cost of biochar. These results suggest that the biochar application can significantly improve the SOC sequestration and reduce the CF, but also had negative effect on NEEB in paddy filed.

Increasing planting density can improve the yield of Tartary buckwheat.

Planting densities and nitrogen fertilizer application rates determine the yield of crops. Tartary buckwheat is a pseudocereal crop with great health care and development values. However, little is known about application of nitrogen fertilizer and planting density on the physiological characteristics of Tartary buckwheat. This study aims to clarify the effect of planting density on the senescence and yield of Tartary buckwheat under low nitrogen conditions. A 2-year field experiment was conducted on Tartary buckwheat (Jinqiao 2) to study the effects of different planting densities (8 × 105, 10 × 105, 12 × 105, 14 × 105, and 16 × 105 plants·ha-1) on the root morphology and activity, chlorophyll and malondialdehyde (MDA) contents, antioxidant enzyme activity, photosynthetic characteristics, agronomic traits, and yield of Tartary buckwheat in the absence of nitrogen fertilizer treatment. With the increase in planting density, the root morphological indices and activities; chlorophyll a, chlorophyll b, and carotenoid contents; superoxide dismutase and peroxidase activities; net photosynthetic rate; transpiration rate; intercellular CO2 concentration and transpiration rate; main stem node, branch, and leaf numbers; grain number and weight per plant; and 1000-grain weight of Jinqiao 2 decreased continuously, whereas plant height and leaf MDA content increased continuously. The yield of Tartary buckwheat first increased and then decreased with the increase in planting density. The yield under 14 × 105 plants·ha-1 treatment increased by 68.61%, 44.82%, 11.00%, and 22.36%, respectively, relative to that under 8 × 105, 10 × 105, 12 × 105, and 16 × 105 plants·ha-1treatments. In summary, planting at an appropriately high density (14 × 105 plants·ha-1) can promote the increase in the yield of Tartary buckwheat populations under low nitrogen conditions and is recommended for use in production to achieve the high-yielding and nitrogen saving cultivation of Tartary buckwheat. This research can serve as a theoretical basis to jointly achieve the high yield and nitrogen saving of Tartary buckwheat.

Optimizing Initial Nitrogen Application Rates to Improve Peanut (Arachis hypogaea L.) Biological Nitrogen Fixation

The application of nitrogen fertilizer is crucial to the growth and biological nitrogen fixation of peanut, especially in the seedling stage where nodules have not yet formed. However, it is still uncertain how much initial nitrogen fertilizer should be applied to promote peanut root growth, nodule formation, and biological nitrogen fixation (BNF). There, a 2-year pot experiment was conducted using Huayu 22 (HY22, large-grain cultivar) and Huayu 39 (HY39, small-grain cultivar) as experimental materials to research the effects of different initial nitrogen fertilizer application rates on peanut root growth (root weight, root length, root mean diameter, root activity) and biological nitrogen fixation capacity (nodule number, nodule weight, biological nitrogen fixation, and nitrogen fixation potential per plant). N0, as control, four initial nitrogen fertilizer application rates were established: 15 kg·hm−2 (N15), 30 kg·hm−2 (N30), 45 kg·hm−2 (N45), and 60 kg·hm−2 (N60). The present results showed that the nodule number, nodule dry weight, nitrogenase activity, and biological nitrogen fixation of the HY22 cultivar under the N15 treatment were higher compared to those under other treatments over the two growing seasons. In addition, the cultivar of HY39 treated with the N15 treatment also increased the nitrogen fixation potential per plant and BNF relative to other treatments. Although the application of 60 kg·hm−2 nitrogen increased the root surface area and root volume, it decreased the nitrogenase activity, nodule dry weight, and nitrogen fixation potential per plant of HY22 and HY39 varieties in both growing seasons. Above all, an initial nitrogen application of 15 kg·hm−2 may be the optimal treatment for promoting peanut nodule formation and biological nitrogen fixation.

Maize-soybean intercropping improved maize growth traits by increasing soil nutrients and reducing plant pathogen abundance

IntroductionMaize (Zea mays L.)–soybean (Glycine max L.) intercropping has been widely utilized in agricultural production due to its effectiveness in improving crop yield and nutrient use efficiency. However, the responses of maize rhizosphere microbial communities and the plant pathogen relative abundance to maize growth traits in maize-soybean intercropping systems with different chemical nitrogen fertilizer application rates remain unclear.MethodsIn this study, a field experiment was conducted, and the bacterial and fungal communities of maize rhizosphere soils in maize-soybean intercropping systems treated with different N fertilization rates were investigated using Illumina NovaSeq sequencing. Maize growth traits, soil physicochemical properties and soil enzyme activities were also examined.Results and discussion:We found that intercropping and N fertilizer treatments strongly influenced soil microbial diversity, structure and function. The PLSPM (partial least squares path modeling) confirmed that soil nutrients directly positively affected maize biomass and that intercropping practices indirectly positively affected maize biomass via soil nutrients, especially NH4+-N. Intercropping agronomic approaches also improved maize growth traits by reducing the plant pathogen abundance, and the relative abundance of the plant pathogen Trichothecium roseum significantly decreased with intercropping treatments compared to monocropping treatments. These results confirmed the benefits of maize-soybean intercropping treatments for agricultural production.

Water and Nitrogen Balance under Various Water and Fertilizer Regulation Modes

A experiment was conducted at the Jiangxi Province Center Station of Irrigation Experiment from 2019 to 2021 to study the water and nitrogen balance under water and fertilizer regulation modes. The study aimed to propose a recommended mode for paddy fields that could save water, control pollution, reduce gas emission, and improve fertilizer use efficiency. This study examined the impact of different irrigation methods and nitrogen application levels on water saving and emission reduction in paddy fields. The experiment included six treatments, which involved two irrigation methods (intermittent irrigation and flooding irrigation, referred to as W1 and W0, respectively) and three application rates of nitrogen fertilizer (0 kg/ha, 135 kg/ha, 180 kg/ha, referred to as N0, N1 and N2, respectively). The study found that irrigation methods had a significant effect on the amount of irrigation, drainage, leakage, nitrogen load from drainage, soil nitrification potential, and ammonia volatilization. The results showed that compared to flooding irrigation, intermittent irrigation reduced the amount of irrigation, drainage, leakage and nitrogen load from drainage by an average of 25.98%, 16.03%, 8.43% and 10.86%, respectively. However, the study also found that the nitrification potential and ammonia volatilization increased by an average of 6.45% and 4.32%, respectively. Fertilization levels had a significant effect on drainage nitrogen load, early soil nitrification potential and ammonia volatilization. Compared with the treatment of N2 (180 kg N/ha), the drainage nitrogen load under the treatment of N1 (135 kg N/ha) decreased by 10.86% on average, while nitrification potential and ammonia volatilization increased by 38.74% and 3.33%, respectively. In terms of nitrogen output, the amount of nitrogen absorbed by crops was the largest, followed by the nitrogen load from field drainage, then ammonia volatilization, and then denitrification. Considering the goals of water saving, emission reduction, and the efficient utilization of water and fertilizer in paddy fields, the optimal water and fertilizer regulation mode was the W1N1 mode (intermittent irrigation combined with reduced nitrogen fertilizer application rate, 135 kg N/ha).

Variance-based global sensitivity analysis and uncertainty quantification of the AquaCrop model parameters for basil (Ocimum basilicum L.) under different nitrogen fertilizer rates

Dynamic crop models are powerful tools for evaluating crop responses to alternative management options. These models consist of various input parameters that need calibration before being implemented in a new environment. Sensitivity analysis (SA) has proven to be an efficient method for identifying dominant model parameters. This study aimed to determine influential parameters of the AquaCrop model for basil and also quantify output uncertainty under different nitrogen fertilizer rates. The Sobol’ SA method was employed to compute both first-order and total-order sensitivity indices. Results indicated that normalized water productivity (WP*) and crop coefficient (KcTr,x) were the most influential parameters across all treatments. Furthermore, as fertility stress increased, the interaction effects among parameters decreased. The temporal analysis of model output (biomass) revealed that parameter sensitivities were highly time-dependent. In addition, the uncertainty of predicted biomass was determined using combined violin and box plots. Results demonstrated that the optimal nitrogen fertilizer application rate extended the distribution of model output. In summary, these findings offer valuable insights for model simplification and effective decision-making.

The effect of land-use conversion from agriculture to perennial biomass crops and nitrogen fertilizer on soil organic carbon stock in southern Ontario, Canada

Switchgrass [Panicum virgatum, (SG)] and miscanthus [Miscanthus spp., (Mis)] are perennial biomass crops (PBCs) commonly grown in Ontario, Canada. By the integration of PBCs on marginal/degraded agricultural (Ag) fields, a positive gain in soil organic carbon (SOC) sequestration has been reported in the scientific literature. Therefore, using PBCs to enhance SOC sequestration can potentially contribute to Canada's goal to reach net-zero greenhouse gas emissions by 2050. However, long-term field research (>10 years) to clearly demonstrate this trend in Canada is limited. In the above context, this study compared the current SOC stock (Mg C ha−1) in SG and Mis to that of baseline Ag SOC obtained from three different locations, namely Elora (2008–2019), Guelph (2009–2020) and Burlington (2016–2020), Ontario, Canada. SOC stock at the time of land-use conversion from Ag to SG and Mis was considered as baseline. Woodlots (WLs), undisturbed natural forests, were used as reference SOC (potential maximum SOC stock) to predict the potential SOC sequestration in the future by PBCs at the respective locations. Results showed that SOC stocks in all SG fields, Mis fields and WLs were higher compared to respective baseline Ag fields. SOC stocks (Mg C ha−1) in PBCs were significantly higher in Elora (SG: 96.3 ± 3.44, Mis: 100.0 ± 1.48) and Guelph (SG: 88.5 ± 5.72, Mis: 87.9 ± 6.43) over 11 years, whereas SOC stock in Burlington (SG: 87.5 ± 5.04, Mis: 94.7 ± 4.86), showed no significant difference over 4 years compared to their respective baseline Ag fields (77.6 ± 3.09, 59.3 ± 1.17 and 84.1 ± 3.39). All WLs had significantly higher SOC stock compared to their respective baseline Ag fields, showing the potential for future SOC stock gain by PBCs. SOC stock values in SG, with different nitrogen (N) fertilizer application rates (0, 40, 80 and 160 kg N ha−1), were not significantly different. Conversely, SOC stock at all N rates were significantly higher in SG than baseline Ag SOC stock values. For Mis, only N fertilizer rates 40, 80, 160 kg N ha−1 significantly increased SOC stock. However, within the four N fertilizer rates, SOC significantly increased only at 80 kg N ha−1. Increases in SOC stock suggest that converting marginal lands to PBCs over the long-term (>10 years) could create additional terrestrial C sinks. In Canada, there are close to 10 million ha of degraded Ag lands that can potentially be repurposed for PBCs, therefore the conversion of these unproductive Ag lands to PBCs could significantly contribute to Canada's climate mitigation strategies.

Different manure management methods impact on nitrogen use efficiency - comparison of four dairy farms in Hokkaido Japan

Different manure management methods impact on nitrogen use efficiency - comparison of four dairy farms in Hokkaido Japan

Transcriptome Analysis of Nitrogen-Deficiency-Responsive Genes in Two Potato Cultivars

The potato is the third largest food crop, and nitrogen fertilizer is important for increasing potato yields; however, the shallow root system of potatoes causes the nitrogen fertilizer utilization rate to be low, which results in waste and environmental pollution, meaning that high nitrogen efficiency breeding is highly significant for potatoes. In the high nitrogen efficiency breeding of potatoes, genes with a nitrogen-deficient response should first be identified, and RNA-seq is an efficient method for identifying nitrogen-deficiency-response genes. In this study, two potato cultivars, Dongnong 322 (DN322) and Dongnong 314 (DN314), were utilized, and two nitrogen fertilizer application rates (N0 and N1) were set for both cultivars. Through the determination of physiological indicators, we identified that DN314 is more sensitive to nitrogen fertilizer, while DN322 is relatively insensitive to nitrogen fertilizer. Samples were taken at the seedling and tuber formation stage. At the seedling stage, DN322 and DN314 had 573 and 150 differentially expressed genes (DEGs), while at the tuber formation stage, they had 59 and 1905 DEGs, respectively. A total of three genes related to a low-nitrogen response were obtained via the combined analysis of differentially expressed genes (DEGs) and weighted correlation network analysis (WGCNA), of which two genes were obtained at the tuber formation stage and one gene in the seedling stage, providing theoretical guidance for the high nitrogen efficiency breeding of potatoes.

The Use of Faba Bean Cover Crop to Enhance the Sustainability and Resiliency of No-Till Corn Silage Production and Soil Characteristics

Sustainable corn production requires a dramatic shift toward natural soil fertility rather than relying solely on synthetic fertilizers. Cover crops play an important role in improving the productivity of subsequent row crops through improving soil properties. The main goal of this study was to investigate if increasing cover crop biomass through applying a higher density can enhance soil characteristics in the short term and contribute more nitrogen to succeeding corn silage. In a two-year field study (2018–2019), the influence of faba bean (Vicia faba L.) as a cover crop on soil characteristics and corn silage (Zea mays L.) production was evaluated. Treatments consisted of five levels of faba bean density (0, 25, 35, 40, and 80 plants m−2) and four application rates of urea-based nitrogen fertilizer (0, 100, 200, and 300 kg ha−1) in a no-till system. The measured soil characteristics were not significantly affected through increasing cover crop density to 80 plants m−2. The faba bean roots comprised 33% of total biomass in densities ranging from 25–40 plants m−2. The highest total N yield (root + shoot) was 133 kg N ha−1, obtained from 40 faba bean plants m−2. The faba bean root decomposed faster than the shoot, and the addition of N to the corn accelerated 50% N release from the roots but had no significant effect on shoot decomposition. Corn planted after 40 plants m−2 faba bean yielded 28% more than the corn with no faba bean. Corn yielded less in no-cover-crop fields even when it received the highest synthetic N rate (300 kg N ha−1), indicating the value of including faba bean in rotation with corn.

Development of a cotton fiber quality simulation module and its incorporation into cotton crop growth and development model: GOSSYM

GOSSYM is a mechanistic, process-level cotton crop simulation model. It can simulate the growth and development of cotton under different environmental and management conditions and provide information on crop growth and development, various stresses, and yield. The current model version does not have the capability of simulating cotton fiber quality. Cotton fiber quality is as significant as fiber quantity. In this study, a cotton fiber quality simulation module is developed and integrated into GOSSYM. The functional relationships between the fiber quality and the major factors influencing fiber quality (temperature, water, and nutrient status) are established based on the temperature, water, and nutrient-controlled sunlit soil plant atmospheric research (SPAR) chamber experiments. In the developed model, the potential fiber quality in terms of four major fiber quality indices (fiber length, fiber strength, micronaire, and uniformity) is estimated based on the temperature function, and actual fiber quality indices are determined by reducing potential quality as a function of water and nutrient status in the crop. The newly developed model's fiber quality modeling capabilities are demonstrated using illustrative examples from a case study. Illustrated examples analyze the effect of different temperatures, nitrogen fertilizer application rates, irrigation, planting date, and atmospheric carbon dioxide concentrations on fiber quality indices. Simulation results are discussed by correlating them with underlying processes (growth and development, water, and nitrogen status), literature data, and functional relationships incorporated into the fiber quality module in GOSSYM. The model has demonstrated a reasonable simulation of fiber quality. The developed model can be a valuable tool for accurate cotton fiber quality simulations, lint yield production, fiber quality optimization, and making policy decisions under varying environmental and management conditions.