Nitrogen Fertilizer Rates Research Articles

Variation of Some Agro-Physiological and Biochemical Parameters of Wheat (Triticum aestivum L.) Varieties in Response to Nitrogen Fertilizer Rates at Djirataoua in Southern Niger Republic

Nitrogen is the most limiting plant nutrient element of soils in Niger. Farmers apply nitrogen to increase yield of cereal crops. A survey conducted at Djirataoua in southern Niger, revealed that wheat growers applied nitrogen fertilizer with less technical knowledge resulting in low response on growth and yield. To produce suitable recommendations to farmers, a field experiment was conducted during two dry seasons (2016/2017 and 2017/2018) at Djirataoua (13°25’59’’N, 7°8’12’’E). The aim of the study was to determine the optimum level of Nitrogen for highest yield and agro-physiological parameters of wheat varieties. Four Nitrogen levels (0, 100, 150 and 200 kg N ha-1) and four wheat varieties were evaluated in this study. The experiment was laid out in a split plot design with three replications. Data collected on grain yield, chlorophyll, Nitrogen uptake and protein content were subjected to the analysis of variance and mean comparison. The results showed that application of 150 kg N ha-1 Nitrogen resulted in highest grain yield (3202 kg ha-1), chlorophyll content (50.9 SPAD) N uptake (72.63 kg ha-1), and protein content (135.5 g kg-1). The wheat varieties were significantly different in these parameters. Reyna-28 and Sokoll/3/ produced higher grain yield and Nitrogen uptake. Higher protein content was observed in Norman and Sokoll/3/. Significant interactions were observed between Nitrogen rates and variety on yield characters, Nitrogen uptake and protein content. The highest grain yield, Nitrogen uptake and chlorophyll content were achieved by interaction of Reyna-28 and Sokoll/3/ with 150 kg N ha-1. Therefore, application of 150 kg N ha-1 and using varieties Reyna-28 or Sokoll/3/ is recommended to farmers for maximum grain yield and high protein content.

Reducing ammonia volatilization in rice paddy: the importance of lower fertilizer rates and soil incorporation

In rice paddies, which exhibit higher ammonia (NH₃) emission factors than upland soils, identifying key drivers of NH₃ flux intensity is crucial. Contrary to the commonly held view that NH₃ flux is primarily governed by soil ammonium (NH₄⁺) concentrations, we found no significant relationship between NH₃ flux and NH₄⁺ levels in the soil during rice cultivation. To pinpoint a primary factor influencing NH₃ flux intensity under conventional rice cropping practices, we conducted a 2-year field study applying four nitrogen (N) fertilization rates (0, 45, 90, and 180 kg N ha⁻¹) using urea [(NH₂)₂CO], the most common N fertilizer. NH₃ emissions were tracked using the ventilation method. Following N application, NH₃ flux sharply increased but rapidly returned to baseline. Half of the N applied as a basal fertilizer was incorporated within the soil, contributing only 10% of total NH₃ emissions. In contrast, top-dressed applications—20% of total N at the tillering stage and 30% at panicle initiation—accounted for approximately 90% of NH₃ loss. Seasonal NH₃ flux increased quadratically with rising N application rates, correlating strongly with NH₄⁺ concentrations in floodwater rather than soil. Grain yield responded quadratically to N levels, peaking at 120 kg N ha⁻¹ with a 37% increase over control yields. NH₃ flux intensity, defined as seasonal NH₃ flux per unit of grain yield, showed a quadratic response to N fertilization, decreasing with initial fertilizer additions (up to 38 kg N ha⁻¹) but then sharply increased with further N fertilization increase. Hence, reducing NH₄⁺ concentrations in floodwater through moderated N application and deeper fertilizer placement could be essential for minimizing NH₃ volatilization in rice systems.

Logistic and Structural Equation Fitting Analyses of the Effect of Slow-Release Nitrogen Fertilizer Application Rates on the Nitrogen Accumulation and Yield Formation Mechanism in Maize

The purpose of this study is to clarify the differential effects of the application rate of slow-release nitrogen fertilizer (SRFN) on the nitrogen (N) accumulation dynamics, nutrient organ N distribution and transportation, yield, and N utilization efficiency of maize harvested using grain-type machines. This has significant implications for the scientific application of SRFN, as well as for reducing its application rate and improving its efficiency, in the agro-pastoral transitional zone of northern China. In a long-term positioning experiment that began in 2018, five treatments consisting of different SRFN application rates were set up, namely, N120 (120 kg ha−1), N180 (180 kg ha−1), N240 (240 kg ha−1), N300 (300 kg ha−1), and N360 (360 kg ha−1), with no fertilization during the growth period used as control (CK) treatment. To explore the characteristics of nitrogen accumulation dynamics in maize populations and the main factors affecting maize yield formation under the different SRFN application rate treatments, this study adopted a combination of quantitative analyses and model fitting, including logistic models, principal component analysis, and structural equation modeling. The research results show that SRFN application increased the aboveground N accumulation of the maize population, and the fitting effect of the logistic models was significant. The maximum rate of N accumulation in both years showed a trend of first increasing and then decreasing with the increase in the SRFN application rate. Compared with CK, SRFN application reduced the proportion of N distribution in the nutrient organs during the R6 stage, and it increased the N transport from the nutrient organs to the grains after the VT-R1 stage. With the increase in the SRFN application rate, both the economic yield and biological yield showed a single peak curve change and were maximized in the N240 treatment. The economic yield reached 15,342.07 kg ha−1 in 2020 and 16,323.51 kg ha−1 in 2021, increasing by 36.2% and 61.7% compared with CK, respectively. The apparent N fertilizer recovery rate, N uptake efficiency, N agronomic efficiency, and N fertilizer partial productivity all gradually decreased with the increase in the SRFN application rate. In maize populations, an appropriate SRFN application rate can adjust the characteristic parameters during the aboveground N accumulation rapid growth period, increase the N accumulation amount in aboveground parts, promote the transport of N from nutrient organs to grains, and improve yield. An application of 180–240 kg ha−1 SRFN is recommended for maize cultivation in the agro-pastoral transitional zone of northern China, as it is beneficial for stabilizing and increasing maize yield, as well as reducing the rate and improving the efficiency of N fertilizer.

Optimizing Irrigation and Nitrogen Levels for Enhanced Cabbage Growth in Yobe's Semi-Arid Region

This study investigated the effects of irrigation schedules and nitrogen fertilizer application rates on the growth and productivity of cabbage in Damaturu, Yobe State. Using a Randomized Complete Block Design (RCBD) in a 3x5 factorial arrangement with three replications, we tested three irrigation intervals “3, 6, and 9 days” and five nitrogen fertilizer levels “0, 25, 50, 75, and 100 kg ha⁻¹” on an improved cabbage variety (Datdiku-5m). Results indicated cabbage growth positively responded to optimal irrigation intervals and increasing nitrogen fertilizer rates. The combination of 6-day irrigation intervals and 100 kg ha⁻¹ of nitrogen fertilizer resulted in impressive outcomes: a tallest head height of 18.92 cm, the largest head diameter of 16.95 cm, maximum plant height of 24.92 cm, the largest plant spread of 37.12 cm, a maximum marketable yield of 63.5 t/ha, and the highest total yield of 71.52 t/ha (Table 3). This combination ensures an adequate supply of water and nutrients, promoting robust growth and significant yield in semi-arid region. In contrast, lower irrigation intervals (9 days) and reduced nitrogen levels (0-50 kg ha⁻¹) led to stunted growth and lower productivity metrics, illustrating the critical role of proper water and nutrient management in achieving optimal cabbage yields. Therefore, adopting a 6-day irrigation schedule and applying 100 kg ha⁻¹ of nitrogen fertilizer may effectively increase cabbage yield. Future research should explore different nitrogen fertilizer rates and the combined effects of various nutrients with different irrigation intervals to further assess their impact.

Response of Yield of Shallot (<i>Allium ascalonium</i> L.) to Nitrogen Fertilizer Rates and Spacing Under Irrigation at Mulo, Ethiopia

The shallot (<i>Allium ascalonium</i> L.) is one of the important alliaceous crops cultivated in many tropical countries. It is an important horticultural crop used to flavor the local stew "wot" and a source of income for farmers in Ethiopia. However, the productivity of shallot is low at study area due to various limiting factors such as low soil fertility, plant population and lack of improved agronomic practices. A field experiment was conducted to investigate the effect of intra-row spacing and nitrogen fertilizer levels on growth, yield and quality of shallot at Mulo District, Oromia Regional state, Ethiopia during 2021/22 off season. The treatments consisted of four intra-row spacing (5, 10, 15 and 20) cm and four levels of nitrogen fertilizer (0, 50, 100 and 150) kgNha<sup>-1</sup> tested in a randomized complete block design with three replications. Data on shallot yield was collected. The interaction effect of intra-row spacing and nitrogen fertilizer influenced the marketable yield, unmarketable yield, bulb weight, bulb fresh weight, bulb dry weight, dry matter and total yield. As a result, the treatment combination of 150kgha<sup>-1</sup> nitrogen and 15cm intra-row spacing yielded the highest net benefit of shallot (Eth-Birr 1,012,274), followed by the treatment combination of 150kgha<sup>-1</sup> nitrogen and 20 cm intra-row spacing. In conclusion, the above findings indicated that the combined application of 150kgNha<sup>-1</sup> with 15 cm spacing can improve shallot growth and productivity in the Mulo district area. However, more research needs to be done in different seasons and locations, taking into account the application rate of nitrogen fertilizer and different intra-row spacing, to generate more reliable information.

Relationships Between Photosynthetic Efficiency and Grain Antioxidant Content of Barley Genotypes Under Increasing Nitrogen Rates

Nitrogen fertilization may affect the functioning of photosynthesis as well as the chemical composition and antioxidant potential of cereal grains. Little is known about the relationship between the efficiency of photosynthesis and the content of phenolic compounds in barley grain, especially in conditions of varying nitrogen availability. In this regard, a field experiment was conducted to examine the responses of two primary barley genotypes with elevated phenolic compound content (TPC) in grain and an intensive modern cultivar H. v. vulgare with high protein content to increasing nitrogen fertilization (rates of 0, 30, 60 and 90 kg N ha−1) during the study years, which differed in terms of hydrothermal conditions. The leaf greenness index (SPAD) and chlorophyll fluorescence parameters were evaluated on three occasions throughout the growing season. Following the harvest, the chemical composition of the grains, including phenolic acids, flavonoids and antioxidant potential, was evaluated. The antioxidant potential and chemical composition of the grain, including TPC and protein content, depended to the greatest extent on genetic and environmental factors, and only then on nitrogen fertilization. Nitrogen increased the TPC content and antioxidant capacity ABTS+ of the grains of all studied genotypes and the protein content in H. v. vulgare grain. Rates of 60 and 90 kg N ha−1 resulted in a significant increase in the SPAD, PIabs and Fv/Fm in BBCH 34 and 57. A positive correlation was confirmed between the SPAD and PIabs and the content of TPC and ABTS+ in the grain. The dependence of qualitative characteristics on the Fv/Fm was also demonstrated. The primary genotypes are characterized by a greater genetic potential for the synthesis of phenolic compounds than the modern cultivar H. v. vulgare. The synthesis of phenolic compounds, and thus their accumulation in the grain, is clearly stimulated by unfavorable environmental factors and moderate nitrogen rates and depends on the chlorophyll content in the leaves and the efficiency of photosynthesis. N fertilization has a beneficial effect on the content of phenolic compounds in grain resulting from the improvement in the SPAD and PIabs. The chemical composition of grain and the increase in antioxidant potential are determined by the Fv/Fm, which is low under hydrothermal stress conditions.

Fertilizer nitrogen rate effects on broiler litter–fertilized corn: Grain yield and nutrient composition

AbstractNitrogen (N) plays an important role in corn (Zea mays L.) production, but little is known of optimum fertilizer N rates for corn grain yield and nutrient composition when poultry manure such as broiler litter (BL) (Gallus gallus domesticus) is applied. Typically, farmers consider BL as a soil conditioner and often do not discount the N contribution from the BL application. Field experiments were conducted in 2020 and 2021 over three diverse environments across Alabama to determine the agronomic optimum nitrogen rate (AONR) for BL–fertilized dryland corn with five side dress fertilizer N rates (0, 84, 140, 196, and 252 kg N ha−1). The study utilized a yield response curve and evaluated the effect of fertilizer N rate on grain nutrient composition. BL (4.48 Mg ha−1 equivalent to 2‐ton acre−1) was applied to the study sites before planting each year. The AONRs for grain yield across these environments varied from 114 to 223 kg N ha−1 (0.013–0.027 kg of fertilizer N per kg of grain yield ha−1). The predicted grain yield at the AONRs ranged from 4.22 to 13.27 Mg ha−1. Grain N concentration increased with increasing fertilizer N rate. However, the weak to nonexistent correlation between fertilizer N and other grain nutrient elements suggests that raising the fertilizer N rate does not necessarily lead to higher nutrient levels in corn grain. Overall, these findings could be useful for developing N management guidelines for corn fields that receive BL in Alabama.

Nutrient Use Efficiency and Cucumber Productivity as a Function of the Nitrogen Fertilization Rate and the Wood Fiber Content in Growing Media.

A peat substrate is made from peat from drained peatlands, which is a limited resource. A realistic estimate is that 50% of the world's wetlands have been lost. Peat is used in horticulture, especially for the cultivation of vegetables in greenhouses. The consequences of peatland exploitation are an increase in the greenhouse effect and a decrease in carbon stocks. Wood fiber can be used as an alternative to peat. The chemical properties of growing media interact and change continuously due to the small volume of growing media, which is limited by the growing container. This study aims to gain new knowledge on the impact of nutrient changes in the microbial degradation of carbon compounds in wood fiber and mixtures with a peat substrate on the content and uptake of nutrients required by plants. The cucumber (Cucumis sativus L.) variety 'Dirigent H' developed in the Netherlands was cultivated in growing media of a peat substrate and wood fiber: (1) peat substrate (PS); (2) wood fiber (WF); (3) wood fiber and peat substrate 50/50 v/v (WF/PS 50/50); (4) wood fiber and peat substrate 25/75 v/v (WF/PS 25/75). The rates of fertilization were the following: (1) conventional fertilization (CF); (2) 13 g N per plant (N13); (3) 23 g N per plant (N23); (4) 30 g N per plant (N30). The experiment was carried out with three replications. As the amount of wood fiber increased, the humidity and pH of the growing media increased. The fertilization of the cucumbers with different quantities of nitrogen influenced the nutrient uptake. The plants grown in the 50/50 and 25/75 growing media had the best Cu uptake when fertilized with N23. When the plants grown in the wood fiber media and the 50/50 media were fertilized with N13, N23, and N30, the Mn content in the growing media at the end of the growing season was significantly lower than the Mn content in the media with conventional fertilization. Thus, nitrogen improved the uptake of Mn by the plants grown not only in the wood fiber, but also in the combinations with a peat substrate. Growing plants in wood fiber and fertilizing them with N13 can result in the optimum uptake of micronutrients. The number and biomass of cucumber fruits per plant were influenced by the amount of wood fiber in the growing media and the application of nitrogen fertilizer. The highest number of fruits and biomass of fruits per plant obtained were significantly higher when the cucumbers were grown in WF/PS 50/50 growing media with additional N13 fertilization.

The effect of nitrogen fertilisation, biostimulant application and extra-root phosphorus fertilization on yield and quality of malting barley grain

A series of small-plot field trials were conducted between 2019 and 2021 with the spring barley variety Francin. The impact of Vital Root and YaraVita KOMBIPHOS on the grain quality of malting barley at varying nitrogen fertilization rates (50 kg·ha-1 N, 70 kg·ha-1 N, 90 kg·ha-1 N, and 110 kg·ha-1 N) was investigated. The following parameters were evaluated: grain size, thousand grain weight, specific weight, starch content, and protein content. The portion of grain <2.5 mm, weight of thousand grains, and specific weight decreased with increasing nitrogen fertilization. Additionally, a decrease in starch content was observed with an increase in protein content in the grain. The application of Vital Root and YaraVita KOMBIPHOS at lower nitrogen fertilization rates up to 70 kg·ha-1 N had a positive effect on grain quality.

Combination of nitrogen and organic fertilizers reduce N2O emissions while increasing winter wheat grain yields and quality in China

Wheat grain yields, quality, and nitrous oxide (N2O) emissions were controlled through the type and application rate of nitrogen (N) fertilizer. Here, we investigated the optimal management of N fertilization by examining the combined effects of organic and N fertilizers on wheat yields, quality, and N2O emissions. Field trials under six treatments were located on campus farms at Anhui Science and Technology University, including farmer’s common practice (270 kg N ha-1, N270), 2/3 reduction in N270 (90 kg N ha-1, N90), organic fertilizer with equal N270 (OF270), 2/3 reduction in OF270 (OF90), 4/5 reduction OF270 + 1/5 reduction N270 (20% OF270 + 80% N270), and 4/5 reduction OF90 + 1/5 reduction N90 (20% OF90 + 80% N90) were applied to winter wheat. The plots were arranged in a randomized complete block experimental design. The N2O emissions were quantified under different fertilization measures in the peak wheat growing season during sowing, jointing, and grain filling stages, respectively. Compared with N270 and N90 treatments, N2O emissions were significantly decreased by 18.6% and 27.2%, respectively, under 20% OF270 + 80% N270% and 20% OF90 + 80% N90 (p < 0.05). Further, N2O emissions in N270 were increased by 50.8% relative to N90. Wheat yields increased significantly under 20% OF90 + 80% N90 by 27.6% (N270) and 16.4% (N90), and were considerably enhanced under 20% OF270 + 80% N270 by 40.6% (N270) and 12.7% (N90) in contrast to OF270 and N270 (p < 0.05). Compared with N90, the content of wet gluten, protein and starch under 20% OF90 + 80% N90 treatment significantly increased by 7.7%, 13.8% and 7.9%, and enhanced by 7.6%, 4.8%, 8.0% relative to OF90, respectively (p < 0.05). The starch content increased significantly by 2.0%, whereas the settlement value decreased considerably by 2.9% under 20% OF270 + 80% N270 (p < 0.05), and there was no notable difference in the wet gluten and protein contents (p > 0.05). Our findings indicated that organic fertilizer mixed with N fertilizer can effectively reduce N2O emissions, increase both the grain yields and quality in wheat field compared with N fertilizer alone.

Effects of Various Herbicide Types and Doses, Tillage Systems, and Nitrogen Rates on CO2 Emissions from Agricultural Land: A Literature Review

Although herbicides are essential for global agriculture and controlling weeds, they impact soil microbial communities and CO2 emissions. However, the effects of herbicides, tillage systems, and nitrogen fertilisation on CO2 emissions under different environmental conditions are poorly understood. This review explores how various agricultural practices and inputs affect CO2 emissions and addresses the impact of pest-management strategies, tillage systems, and nitrogen fertiliser usage on CO2 emissions using multiple databases. Key findings indicate that both increased and decreased tendencies in greenhouse gas (GHG) emissions were observed, depending on the herbicide type, dose, soil properties, and application methods. Several studies reported a positive correlation between CO2 emissions and increased agricultural production. Combining herbicides with other methods effectively controls emissions with minimal chemical inputs. Conservation practices like no-tillage were more effective than conventional tillage in mitigating carbon emissions. Integrated pest management, conservation tillage, and nitrogen fertiliser rate optimisation were shown to reduce herbicide use and soil greenhouse gas emissions. Fertilisers are similarly important; depending on the dosage, they may support yield or harm the soil. Fertiliser benefits are contingent on appropriate management practices for specific soil and field conditions. This review highlights the significance of adaptable management strategies that consider local environmental conditions and can guide future studies and inform policies to promote sustainable agriculture practices worldwide.

Greenhouse gas emissions during alfalfa cultivation: How do soil management and crop fertilisation of preceding maize impact emissions?

ContextThe use of alfalfa in rotation with intensive crops is common practice to mitigate the physical and chemical issues arising from intensive farming practices. However, there is a dearth of studies on this practice. Given the current concern regarding climate change and the significant impact agriculture has on greenhouse gas (GHG) emissions, understanding the emissions associated with this practice, as well as the most suitable soil and crop management techniques for their mitigation, is of paramount importance. ObjectiveThe present study aimed to (i) quantify emissions of N2O, CO2 and CH4 in an alfalfa crop following a maize cropping scenario; (ii) to determine which tillage system generates the lowest GHG emissions, and; (iii) to determine how N fertilisation from a preceding intensive maize crop affects GHG emissions during alfalfa cropping period. MethodsA three-year field experiment (2019, 2020 and 2021) was conducted to assess the emissions of N2O, CO2 and CH4 from alfalfa cultivation following a three-year period of irrigated maize. Two soil management practices (no-tillage and conventional tillage) were implemented during both the maize cropping period and the alfalfa establishment. Additionally, the nitrogen (N) fertilisation rates applied to the preceding maize crop were included as a treatment (0, 200, and 400 kg N ha⁻¹, corresponding to zero, medium, and high fertilisation levels, respectively) in a randomized block design with two factors. ResultsEmissions of N2O in alfalfa ranged from 0.05 to 0.32 mg N2O-N m⁻² day⁻¹, being significantly higher only during first month of sampling in the treatments that had received fertilisation. CO2 emissions ranged from 1158 to 4258 mg CO2-C m⁻² day⁻¹. Year-average CH4 fluxes were −0.27 g C ha⁻¹ day⁻¹. The average total dry matter produced by alfalfa was 17700 kg ha⁻¹ year⁻¹, being higher for the no-tillage treatment, though significantly so only during first month of sampling. ConclusionsUnder Mediterranean conditions, the tillage system and mineral N fertilizer rates have a relative effect on greenhouse gas emissions during the alfalfa cropping period. Plots without N fertilization initially produced lower N2O emissions and higher total dry matter, resulting in the lowest scaled emissions. For the tillage treatment, no significant differences were found in emission dynamics, which may be due to the fact that alfalfa does not involve soil disturbance, leading to a homogenization of the treatments. However, the NT treatment showed lower scaled emissions due to higher yields in the first year. Therefore, alfalfa cultivation is characterized by low GHG emissions, high yields, and a notable capacity to mitigate the negative effects of previous intensive crops. SignificanceThis study provides data on GHG emissions during alfalfa cropping in the typical Maize-alfalfa crop rotation under Mediterranean irrigated systems, which is useful for new agricultural policies aimed at reducing pollution in the agricultural sector. Additionally, it demonstrates the capability of this crop to mitigate adverse agronomic and environmental conditions caused by preceding intensive farming practices.

Residual Effect of Microbial-Inoculated Biochar with Nitrogen on Rice Growth and Salinity Reduction in Paddy Soil.

Increasing soil and water salinity threatens global agriculture, particularly affecting rice. This study investigated the residual effects of microbial biochar and nitrogen fertilizer in mitigating salt stress in paddy soil and regulating the biochemical characteristics of rice plants. Two rice varieties, Shuang Liang You 138 (SLY138), a salt-tolerant, and Jing Liang You 534 (JLY534), a salt-sensitive, were grown under 0.4 ds/m EC (S0) and 6.84 ds/m EC (S1) in a glass house under controlled conditions. Three types of biochar-rice straw biochar (BC), fungal biochar (BF), and bacterial biochar (BB)-were applied alongside two nitrogen (N) fertilizer rates (60 kg ha-1 and 120 kg ha-1) in a previous study. The required salinity levels were maintained in respective pots through the application of saline irrigation water. Results showed that residual effects of microbial biochars (BF and BB) had higher salt mitigation efficiency than sole BC. The combination of BB and N fertilizer (BB + N120) significantly decreased soil pH by 23.45% and Na+ levels by 46.85%, creating a more conducive environment for rice growth by enhancing beneficial microbial abundance and decreasing pathogenic fungi in saline soil. Microbial biochars (BF and BB) positively improved soil properties (physicochemical) and biochemical and physiological properties of plants, ultimately rice growth. SLY138 significantly had a less severe response to salt stress compared to JLY534. The mitigation effects of BB + N120 kg ha-1 were particularly favorable for SLY138. In summary, the combined residual effect of BF and BB with N120 kg ha-1, especially bacterial biochar (BB), played a positive role in alleviating salt stress on rice growth, suggesting its potential utility for enhancing rice yield in paddy fields.

Effect of Irrigation Depth and Nitrogen Fertilizer Rates on Pepper (Capsicum annum L.) Yield and Water Use Efficiency in Tselemty District, Tigray, Ethiopia

Optimizing agricultural crop production involves utilizing proper irrigation and fertilization techniques. A two-year experiment conducted in the Tselemty district during the off seasons of 2019 and 2020 aimed to assess the impact of varying irrigation levels and nitrogen fertilizer application rates on the growth, yield, and crop water productivity of pepper. The study included three irrigation levels (75%, 100%, and 125% of the required irrigation) and three nitrogen fertilizer application rates (75%, 100%, and 125% of the recommended amount). Analysis of the results using Gen-Stat software revealed that most pepper yield attributes were not significantly affected by the different irrigation and fertilizer levels. However, the marketable yield showed significant variation based on the combined application rates. The research indicates that, under ideal circumstances, the optimal approach for pepper growers is a combination of meeting 100% of the irrigation requirement and applying 100% of the recommended nitrogen fertilizer rate. Nevertheless, in scenarios where water resources are limited and fertilizer expenses are high, a reduced irrigation level of 75% of the requirement coupled with 75% of the recommended nitrogen fertilizer rate could be a viable alternative that does not lead to a substantial decrease in yield.

Soil Test-Based Crop Response Phosphorus Calibration Study on Bread Wheat (Triticum Aestivum L) in Liban Chukala District, East Shewa Zone, Oromia, Ethiopia

Nutrient mining due to sub-optimal fertilizer use on one hand and unbalanced fertilizer use on the other have favored the emergence of multi-nutrient deficiency in Ethiopian soils. Therefore, the study was conducted on twenty-one farmers’ fields in the Liban Chukala District of East Shewa Zone of Oromia, during the main cropping seasons of 2019-2022. The study aimed to determine the economically optimum rate of nitrogen fertilizer in the first year. However, in the second two consecutive years the experiment was conducted to determine phosphorus critical (Pc) and phosphorus requirement factor (Pf and the treatments consisted of six levels of phosphorus (0, 10, 20, 30, 40, and 50) kg ha-1 combined with a single level of nitrogen (69 kg ha1) that gave a total of seven treatments. The experiments were laid out in randomized complete block design (RCBD) with two replications and the gross plot, size was 4 m x 5 m (20 m2) was used to determine phosphorus critical (Pc) and also harvested from 4m2 plot areas. The analysis of variance indicated that, thousand kernels weight, and harvest index were not significantly (p<0.05) influenced by applied NP fertilizers. On the other hand, the analysis of variance indicated that Plant height, spike length, number of seeds per spike, biomass yield, and grain yield were highly significantly (p <0.01) influenced by soil test-based phosphorus fertilizer application. The result indicated that the highest (87.82 cm) plant height, the highest (1013 kg ha-1) biomass, and the highest (4517 kg ha-1) grain yield were recorded by 40 kg P ha-1. Moreover, 23ppm phosphorus critical (Pc) and 9.86ppm phosphorus requirement factor (Pf) were identified for bread wheat production for the farmers of Liban Chukala District.

Optimising Nitrogen Fertilisation in a Potato–Oat Rotation and Implications for Nitrous Oxide Emissions in Volcanic Soils

High nitrogen (N) fertiliser rates are usually applied to increase agricultural yields, leading to high nitrous oxide (N2O) emissions. This is a greenhouse gas that contributes to climate change and depletes the ozone layer. This study aimed to optimise N use efficiency and quantify N2O emission factors (EF1) by measuring the effect of N rates on the yield of a potato-cover crop rotation, apparent N use efficiency (NUE) and N2O emissions. The two-year experiment was carried out on volcanic soils (1.6% carbon, 1.4% N) in southern Chile (40°52′ S, 73°03′ W). Three N application rates were evaluated (80, 150 and 300 kg N ha−1), 35% of which was applied at the planting stage (granular) and 65% at the tubering stage. A control treatment with no N addition was also included. Reducing N fertilisation to 80 kg N ha−1 increased NUE by three times, reduced N2O-N emissions by 33% and reduced emission intensity by 27% without a detrimental impact on crop yield and marketable tuber calibre. No significant difference (p < 0.05) was observed in the N2O emission factor (EF1) because of a low rainfall year. The results suggest that in rainfed agriculture systems, N fertiliser application can be significantly reduced without sacrificing potato yield, favouring the economic and environmental sustainability of potato production.

Effects of Fertilization and Drip Irrigation on the Growth of Populus × canadensis ‘Zhongliao 1’ Plantation and on Soil Physicochemical Properties and Enzyme Activities

Poplars are crucial for timber supply and ecological protection in China. Enhancing the growth of poplar plantations and improving soil fertility in arid, and semi-arid poor soil regions are key aspects of sustainable forest management. Fertilization (FTL) and drip irrigation (DI) are among the most widely used methods globally for increasing yield and soil productivity. This study conducted field experiments on FTL and DI in a 10-year-old Populus × canadensis ‘Zhongliao 1’ (cultivation varieties of P. canadensis in northern China) plantation. DI limits were set according to soil moisture at 60% (S1), 70% (S2), and 80% (S3) of field capacity; nitrogen FTL rates were set at 100% of the baseline fertilization amount (100% BFA, N 643.20 g·year−1, P 473.37 g·year−1, and K 492.29 g·year−1) (F1), 70% BFA (F2), 130% BFA (F3), and 160% BFA (F4). The treatments of drip irrigation and fertigation (DIF) were H1 (100% BFA, 60% FC), H2 (100% BFA, 80% FC), H3 (160% BFA, 60% FC), and H4 (160% BFA, 80% FC), along with a control group (CK) without any management, totaling 12 experimental combinations. The results showed that the H4 had the most significant promoting effect on the height, DBH, and volume increments. All treatments had little effect on the soil bulk density of the plantation but significantly impacted soil capillary porosity and pH. Compared to DI, soil nutrient and organic matter content were more sensitive to FTL. Appropriate FTL and DI can increase soil sucrase activity. Soil urease activity tended to increase with higher FTL rates, and higher DI levels also positively influenced urease activity. Excessive or insufficient soil moisture and nutrients negatively impacted soil cellulase and catalase activities. Correlation analysis revealed no significant correlation between the growth of P. × canadensis ‘Zhongliao 1’ and soil nutrient content, but significant or highly significant correlations existed between growth and soil porosity and related enzyme activities. Comprehensive evaluation using a membership function indicated that high FTL levels (F4) were more conducive to the simultaneous improvement of the growth and soil fertility of the plantation, followed by H4 and F1, suggesting that high FTL is the key factor affecting the growth of 10-year-old P. × canadensis ‘Zhongliao 1’ plantations and the restoration of stand productivity, with moisture being secondary.

Determining Optimal Nitrogen Level and Soil test-based Phosphorus Calibration study for Bread Wheat (Triticum aestivum L.) in Dugda District, East Shewa Zone, Oromia, Ethiopia

Nutrient mining due to sub-optimal fertilizer use on one hand and unbalanced fertilizer use on the other have favored the emergence of multi-nutrient deficiency in Ethiopian soils. Therefore, the study was conducted on twenty-six farmers' fields in Dugda District of East Shewa Zone of Oromia, during the main cropping seasons of 2018-2020. These studies were conducted to determine the economically optimum rate of nitrogen fertilizer in the first year Phosphorus critical (Pc) and phosphorus requirement factor (Pf) in the second year respectively. The treatments consisted of factorial combinations of three levels of TSP (0, 100, and 200) kg ha-1 with six levels of nitrogen (0, 23, 46, 69 92, and 115) kg ha-1 that gave a total of eighteen treatments. However, in the second two consecutive years, the experiment was conducted to determine phosphorus critical (Pc) and phosphorus requirement factor (Pf), and the treatments consisted of six levels of phosphorus (0, 10, 20, 30, 40, and 50) kg ha-1 combined with a single level of nitrogen (69 kg ha-1) that gave a total of seven treatments. The experiments were laid out in randomized complete block design (RCBD) with two replications and the gross plot size was 4 m x 5 m (20 m2) were used to determine optimum nitrogen in the first year and 4m x 5m (20 m2) and phosphorus critical (Pc) and also harvested from 4m2 plot areas. The analysis of variance indicated that Plant height, spike length, number of seeds per spike, biomass yield, and grain yield were highly significantly (p <0.01) influenced by the main effect of nitrogen fertilizer rates. However except for the number of seed per spike, TSP fertilizer significantly (p<0.05) affect plant height and the number of seed per spike as well as highly significantly (p <0.01) biomass and grain yield of bread wheat. The highest (68.76 cm) plant height, the highest (41.02) seed per spike, the highest (8867 kg ha-1) biomass, and the highest (3293 kg ha-1) grain yield were recorded by 200

Towards sustainable fruit production: Identifying challenges and optimization strategies

CONTEXTThe transition to sustainable fruit production is vital for global sustainability and agricultural development. However, implementing these insights into practice faces significant challenges. OBJECTIVESPomelo (Citrus maxima), a prominent citrus species in tropical and subtropical regions, has been cultivated to enhance farmer profitability but increasing yields often comes at the cost of environmental degradation. This study uses pomelo as a case study to assess key factors influencing pomelo production and establish optimal practices that meet consumption-based food while co-benefits for environmental and economic sustainability. METHODSA comprehensive study was conducted by combining 1155 farm surveys (from 2010, 2018, and 2022) with 31 field experiments. Life cycle assessment (LCA), classification and regression tree (CART) analysis, and scenario analysis were employed to develop pathways for sustainable pomelo production in Pinghe County, Fujian Province, China. RESULTS AND CONCLUSIONSResults show no significant differences in pomelo yield across the three years; however, pomelo production in 2022 demonstrated a 60 %–67 % lower in environmental footprints and a 64 %–76 % higher benefit-cost ratio (BCR) compared to 2010 and 2018. Tree age was identified as a critical factor influencing pomelo yield, with optimal yields observed in trees older than 12.5 years. The rate of phosphorus fertilizer application was a key determinant of the phosphorus footprint (PF), which was positively correlated with phosphorus fertilizer rates. Similarly, nitrogen fertilizer application significantly impacted both carbon and nitrogen footprints (CF and NF) as well as the BCR. CF and NF increased with higher nitrogen fertilizer rates, while BCR exhibited a negative correlation with nitrogen fertilizer application. Implementing Science and Technology Backyards (STB) followed by farmer training of slightly more than pomelo nutrient requirements practice (SNRP) or coordinate management by farmers and researchers of matching pomelo nutrients requirement practice (MNRP) had 50 %–91 % lower environmental footprints per ton of pomelo produced and 15 %–44 % higher BCR compared to current farming practices (FP) via reducing 46 %–77 % N, 49 %–92 % P2O5, and 42 %–73 % K2O per hectare. Moreover, adopting 100 % MNRP in pomelo production, along with sustainable fertilizer practices and the implementation of innovative fertilizers, could reduce greenhouse gas (GHG) emissions (0.76 Tg), reactive nitrogen (Nr) emissions (8.76 Gg), phosphorus (P) losses (0.84 Gg), and augment net ecosystem economic benefits (NEEB) (0.94 billion CNY) at the county scale. SIGNIFICANCEOur study provides evidence-based strategies for achieving sustainable pomelo production through multi-stakeholder collaboration of STB, government, enterprises, and smallholders.

Nitrogen fertilization and sowing date as wheat climate change adaptation tools under Mediterranean conditions

In the current situation, climate change has substantially disturbed precipitation occurrence in the Mediterranean region, by increasing its variability and decreasing the total annual amount, which both negatively affect rainfed crop productivity. We hypothesize that a simple cost-effective method for enhancing crop adaptation to new climate conditions would consist of modifying the crop sowing date. Traditional nitrogen (N) fertilization rates could also be adjusted to the current situation given the interdependent water/N relation in plant nutrition. Based on this hypothesis, during a 4-year field experiment with bread wheat (Triticum aestivum L., var. Pistolo), the effects of three sowing dates (October, November, February) and three N fertilization rates (54 kg N ha−1, 27 kg N ha−1, 0 kg N ha−1) on crop development, yield, grain quality, soil N content and N use efficiency were analyzed. The results showed that water scarcity was the predominant limiting factor, because it outweighed N deficiency with half-fertilized crops being as productive as fully fertilized treatments. Nevertheless, sowing date was the most influential factor, with up to a 30 % yield increase noted for the November-sown wheat compared to that sown in October, while delaying wheat sowing to February decreased crop yields. Grain protein content remained the same between the November- and October-sown crops, but increased in the February one crops. Optical sensor measurements showed that an optimal assessment of the current water/N nutritional status of crops can be achieved with these tools.