Fertilizer Rates Research Articles

Participatory Demonstration of Durum Wheat Production Blending Vertisols Management Technologies in Lume District, East Shewa, Ethiopia

Durum wheat production on Vertisols is constrained by waterlogging, where excessive soil moisture limits nutrient availability, resulting in lower yields and higher input demand. Aybar broad bed maker (BBM) was recommended to make broad beds and furrows (BBF) and drain the excess water although it is not widely adopted by farmers. Therefore, this demonstration activity was conducted to create awareness about the importance of BBF along with the recommended fertilizer rates in Lume district during the 2021 and 2022 main cropping seasons. Nine target farmers were purposefully selected based on the ground that their farms are waterlogged Vertisols. Aybar BBM to make the BBF with an 80 cm bed and 20 cm furrow width, while recommended fertilizers at a rate of 92 kg ha<sup>-1</sup> nitrogen (N) and 10 kg ha<sup>-1 </sup>phosphorous (P) were used. The yield data and farmers’ perception were analyzed using t-test, descriptive statistics, and narration, while partial budget analysis was conducted to examine the economic feasibility of the technologies. Results showed that growing durum wheat on BBF by applying the recommended N and P rates resulted in significantly higher grain yield (3474 kg ha<sup>-1</sup>) <i>with a 65.4% yield advantage </i>compared to ridge and furrow (RF) (2100 kg ha<sup>-1</sup>) with the blanket fertilizer rates. The partial budget analysis revealed that land preparation using Aybar BBM, alongside the recommended fertilizer rates, brought a net benefit of 48,563 ETB ha<sup>-1</sup> over the farmers' practice. Likewise, the marginal rate of return for changing from the local plow to Aybar BBM is 901.7%. The farmers also witnessed that the Aybar BBM even takes less plowing time and energy, and they want to continue to use it. <i>In light of these results, the study concludes that the use of Aybar BBM and recommended N and P rates, as a production package on waterlogged Vertisols, is profitable for farmers and recommends promoting and scaling up these technologies in the study area and other waterlogged Vertisols regions of the country.</i>

Deficit Irrigation as an Effective Way to Increase Potato Water Use Efficiency in Northern China: A Meta-Analysis

Water scarcity poses a significant threat to the sustainable production of crops in Northern China. Despite this, the effect of water management practices, such as deficit irrigation, on the yield and WUE of potatoes has been rarely explored. Based on the meta-analysis of field experiment data, this study evaluated the influence of deficit irrigation on potato yield, evapotranspiration (ET), water use efficiency (WUE) and irrigation water use efficiency (IWUE) under variable soil types, water-saving ratio, irrigation methods, soil organic carbon (SOC) content, and fertilizer rate in Northern China. Here, we determined that potato WUE and IWUE were significantly increased by 10.0 and 31.6%, respectively, under deficit irrigation, while ET was significantly decreased by 26.3% compared to full irrigation. Conclusively, deficit irrigation significantly reduced potato yields by 16.4% compared to full irrigation. Furthermore, SOC content played a vital role in improving the WUE and alleviating potato yield losses under deficit irrigation. Our study suggested that maximum WUE with lower potato yield losses under deficit irrigation can be achieved in the Central Plains region of China or in yellow loam soil, brown soil, and meadow soil under alternate root-zone irrigation when the water-saving ratio was less than 45% and fertilizer application rates were 300 kg N ha−1, >240 kg P2O5 ha−1, and 181–300 kg K2O ha−1. Overall, these findings highlight the need for a comprehensive understanding of various agricultural management practices and local environmental conditions to optimize the benefits of deficit irrigation in potato-growing regions across Northern China.

Effects of Fertilizer Application Intensity on Carbon Accumulation and Greenhouse Gas Emissions in Moso Bamboo Forest-Polygonatum cyrtonema Hua Agroforestry Systems.

Agroforestry management has immense potential in enhancing forest carbon sequestration and mitigating climate change. Yet the impact and response mechanism of compound fertilization rates on carbon sinks in agroforestry systems remain ambiguous. This study aims to elucidate the impact of different compound fertilizer rates on soil greenhouse gas (GHG) emissions, vegetation and soil organic carbon (SOC) sinks, and to illustrate the differences in agroforestry systems' carbon sinks through a one-year positioning test across 12 plots, applying different compound fertilizer application rates (0 (CK), 400 (A1), 800 (A2), and 1600 (A3) kg ha-1). The study demonstrated that, after fertilization, the total GHG emissions of A1 decreased by 4.41%, whereas A2 and A3 increased their total GHG emissions by 17.13% and 72.23%, respectively. The vegetation carbon sequestration of A1, A2, and A3 increased by 18.04%, 26.75%, and 28.65%, respectively, and the soil organic carbon sequestration rose by 32.57%, 42.27% and 43.29%, respectively. To sum up, in contrast with CK, the ecosystem carbon sequestration climbed by 54.41%, 51.67%, and 0.90%, respectively. Our study suggests that rational fertilization can improve the carbon sink of the ecosystem and effectively ameliorate climate change.

Mechanized wet direct seeding for increased rice production efficiency and reduced carbon footprint

Crop establishment is one of the major rice production operations that strongly affects rice production, productivity, and environmental impacts. This research introduced a new technology and provided scientific evidence for the benefits of mechanized wet direct seeding (mDSR) of rice as compared with the other crop establishment practices commonly applied by farmers for wet direct seeded rice in Mekong River Delta in Vietnam, such as seeding in line using drum-seeder (dDSR) and broadcast seeding (bDSR). The experiment was implemented across two consecutive rice cropping seasons that are Winter-Spring season and Summer-Autumn season in 2020–2021. Treatments included (1–3) mDSR with seeding rates of 30, 50, and 70 kg ha− 1, (4) dDSR with 80 kg ha− 1 seed rate, and (5) bDSR as current farmer practice with seeding rate of 180 kg ha− 1. The fertilizer application was adjusted as per seeding rate with 80:40:30 kg ha− 1 N: P2O5: K2O with lower seed rate 30 and 50 kg ha− 1 in mDSR; 90:40:30 kg ha− 1 N: P2O5: K2O with medium seed rate of 70 to 80 kg ha− 1; and 115:55:40 kg ha− 1 N: P2O5: K2O with high seed rate of 180 kg ha− 1 in bDSR. Mechanized wet direct seeding rice with a lower seed rate of 30 to 70 kg ha− 1 and fertilizer rate by 22–30% reduced variation in seedling density by 40–80% and in yield by 0.1 to 0.3 t ha− 1 and had similar yield to bDSR. In consequence, N productivity was 27 and 32% higher in mDSR as compared to bDSR during the Winter-Spring season and Summer-Autumn seasons, respectively. The use of lower seed rate and fertilizer in mDSR also led to higher income and lower carbon footprint (GHGe per kg of paddy grains) of rice production than the currently used practices of bDSR. Net income of mDSR was comparable to that of dDSR and higher by 145–220 and 171–248 $US than that of bDSR in Winter-Spring season and Summer-Autumn, respectively. The carbon footprint of mDSR rice production compared to bDSR was lower by 22–25% and 12–20% during the Winter-Spring and Summer-Autumn seasons, respectively. Given the above benefits of farming efficiency, higher income, and low emission, mDSR would be a technology package that strongly supports sustainable rice cultivation transformation for the Mekong River Delta of Vietnam.

Evaluation of five soil nutrient extraction methods for practical assessment of phosphorus and potassium availability for tomato (<i>Solanum lycopersicum</i>) fertilization in Andisols-Garut, Indonesia

Phosphorus and potassium are essential nutrients for plant growth and development. Plants will achieve optimum biomass and production if phosphorus and potassium needs are met through fertilization. Determining the availability of phosphorus and potassium in the soil is essential because it is related to decisions on phosphorus and potassium fertilizer rate recommendations. In this study, we evaluated 5 common phosphorus and potassium extraction methods by correlating the indicated soil nutrient levels to the relative biomass dry weight of tomato plants. The phosphorus and potassium extraction methods used were Mehlich-1, Bray-1, Morgan-Wolf, Ammonium acetate, and HCl-25%. Mean Root Error (MRE) and Root Mean Square Error (RMSE) were used to determine the precision of the linear regression equation model in predicting the relationship between phosphorus and potassium soil extraction methods and the relative biomass dry weight of tomato plants. The correlation of the soil extraction methods used in Andisols with the relative biomass dry weight of tomato was highly significant and very strong (r > 0.75) suggesting that Bray-1 was the best soil-phosphorus extraction method (P<sub>r</sub> = 0.88; P<sub>MRE</sub> = 0.10; P<sub>RMSE</sub> = 4.44), while HCl-25% was the most suitable for soil-potassium extraction (K<sub>r</sub> = 0.90; K<sub>MRE</sub> = 0.05; K<sub>RMSE</sub> = 2.95). The results of the two extraction methods will be used to determine the dosage of phosphorus and potassium fertilizers (<i>nutrient sufficiency approach</i>) for tomato plants grown in Andisols.

Response of Fluted Pumpkin (Telfaria occidentalis) to Varying Rates of Organo-mineral Fertilizer in Obio Akpa, Akwa Ibom State

Response of Fluted Pumpkin (Telfaria occidentalis) to Varying Rates of Organo-mineral Fertilizer in Obio Akpa, Akwa Ibom State

Compost as an Alternative to Inorganic Fertilizers in Cowpea [Vigna unguiculata (L.) Walp.] Production

ABSTRACTSoil fertility management is essential to sustain agricultural production in smallholder farming systems. An experiment was carried out to assess the viability of the combined use of compost and inorganic fertilizers as an alternative to conventional inorganic fertilization under greenhouse conditions. The 10 treatments, arranged in a randomized complete block design (RCBD) with six replications, consisted of a control, conventional mineral fertilization (150 kg NPK ha−1), composts added to the soil alone (2.5, 5, 7.5, and 10 t ha−1), and their combination with 50% of recommended rate of inorganic fertilizers (75 kg NPK ha−1). Application of 7.5 t ha−1 of compost and 50% of the recommended dose of inorganic fertilizer (75 kg NPK ha−1) gave the significantly highest seed yield, corresponding to a 30% increase over NPK‐fertilized plants. The combined application of 2.5 or 10 t ha−1 compost with 75 kg NPK ha−1 increased plant height by 38% compared with the NPK treatment. Additionally, stem diameter increased by 53% when 5 t ha−1 of compost and 75 kg NPK ha−1 were mixed. As expected, control plants produced the most nodules (108), 85% more than inorganic fertilization. Plants fertilized with 7.5 or 10 t ha−1 of compost and 75 kg NPK ha−1 produced 17% more pods, seeds per pod, and seeds per plant than NPK treatments. However, fertilization treatments had no significant effects on cowpea fresh and dry biomass or SPAD values. The results reveal that combining compost with inorganic fertilizer reduced synthetic fertilization by 50%, while producing growth and yields comparable to, or even higher than, recommended inorganic fertilization. This experiment demonstrated that integrated soil fertility management can be used as an alternative to the use of inorganic fertilizers in cowpea cultivation.

Growth and yield response of maize to integrated nutrient management of chicken manure and inorganic fertilizer in different agroecological zones

The productivity of maize, an essential staple food crop in Africa, is severely constrained by the declining fertility of the soil. The combined use of organic and inorganic fertilizers could ameliorate this challenge in a sustainable way to boost maize productivity. Two field trials were conducted at Ashanti -Mampong and Damongo, in the transitional and Guinea Savannah agroecologies of Ghana respectively, to assess the influence of sole and integrated application of chicken manure and NPK fertilizer on the growth and yield of maize. The treatments included two maize varieties; Abontem and Obatanpa, and five fertilizer rates; 3 t/ha chicken manure (CM), NPK (65:38:38 kg ha−1 NPK), ½ CM + ½ NPK and ¾ CM + ¼ NPK and control (no fertilizer). A 2 x 5 factorial randomized complete block design with three replications was used. Significant variations (p < 0.05) were revealed between varieties, fertilizer types and their interaction effects for phenological, growth and yield of maize in both locations. The superiority of the integrated application of NPK and chicken manure was also visible in the vegetative parameters such as plant height, number of leaves and shoot dry weight of the maize plants given them the comparative advantage to assimilate more photosynthates for partitioning to the ears and grains. Obatanpa treated with ½ CM + ½ NPK produced the highest yield of 4661.1 kg ha−1, which was 29.6 and 29.9 % higher than the same variety grown on sole NPK and sole chicken manure, respectively at Damongo. Abontem treated with ¾ CM + ¼ NPK recorded a grain yield of 4479.3 kg ha−1, 11.7 % higher than the sole NPK and 10.3 % higher than the sole CM at Damongo. Similarly, Obatanpa grown on the ½ CM + ½ NPK recorded the highest grain yield of 4349.3 kg ha−1at Mampong followed by Abontem treated with the sole NPK (4267.1 kg ha−1). Sole NPK and the combined application of NPK and chicken manure gave comparable responses for vegetative traits while the integrated application proved superior for grain yield of maize across the two agroecologies.

Evaluation and Participatory Variety Selection of Common Bean (Phaseolus vulgaris L.) Varieties in Dawro Zone, South Western Region of Ethiopia

Farmers in the study area exhibit a unique tendency to choose varieties based on selection criteria rather than tested yields in the district. To ensure farmer participation, a study was conducted on six farmers’ farms, utilizing farmers as replicas in a Randomized Complete Block Design. Ten common bean crop varieties underwent evaluation on these farms to assess varieties in terms of farmer participation and identify priority criteria during the 2019 and 2020 production years. Plot sizes were standardized to 4m plot lengths with inter and intra-spacing of 40cm and 10cm, respectively. The seed and NPSB fertilizer rate were set at 100kg/ha and 122kg/ha, respectively. Significant differences were (P&lt;0.05) were observed among treatments for plant height, days to 50% flowering, days to 90% maturity, and yield over two years. Notably, the common bean varieties Remeda, DAB 96, and SER 119 yielded 1641, 1601, and 1588.7kg/ha, respectively. Additionally, the farmers in the district preferred red-seeded varieties for production and consumption due to superior seed per pod, pod per plant, seed size, seed color, and seed yield. Moreover, these farmers preferred varieties established tolerance to major common bean diseases which were common in the district. Consequently, these high-yielding, farmers preferred, and disease-tolerant varieties are recommended for demonstration and large-scale production in the study regions and agro-ecological zones similar to those the trial was implemented in south western region of Ethiopia.

Effects of unbalanced fertilizer use on system productivity and profitability under rice‐based cropping systems: Evidence from Eastern Gangetic Plain

AbstractUnbalanced nutrient supply is one of the key causes of yield gaps and low farming profitability which impact food insecurity globally. However, the effects of an unbalanced nutrient supply on rice yields and farming profitability have not been quantified for diverse rice‐based cropping systems. To explore the effects, 412 respondents (mostly smallholder farmers) were surveyed in 2019 for the rice crops in three fully rice‐based cropping systems in four agro‐ecological zones of Bangladesh. Two robust estimation approaches namely propensity score matching and endogenous switching regression approaches were used to quantify the effects of unbalanced fertilizer use. The results show that about 68% of farmers in the study areas used unbalanced (over‐doses or under‐doses) nutrient rates relative to government‐endorsed recommendations. Adoption of recommended fertilizer rates was influenced by education, amount of organic manure used, off‐farm income, crop farming‐related training, organizational membership and lack of soil testing tendency. The findings also indicate that adopters of recommended nutrient rates received almost 16% and 46% higher system rice yield and system net return, respectively, relative to non‐adopters. However, based on our research findings, formulation and implementation of effective agricultural policies like effective extension services, strengthening soil testing facilities, increasing organizational membership and targeted awareness programmes could motivate smallholder rice farmers towards adoption of recommended nutrient rates. Adoption of recommended fertilizer rates can significantly enhance crop yields and farming profitability which can boost food security and rural livelihoods in the Eastern Gangetic Plain.

Influence of higher levels of NPK fertilizers on growth, yield, and profitability of three potato varieties in Surma, Bajhang, Nepal

Potato is a crucial food and cash crop with high yield potential in many parts of the Bajhang district. However, achieving optimal yields can be hindered by inconsistent NPK fertilizer application rates and suboptimal potato variety selection, including instances where no fertilizers are used at all by the farmers. To address these challenges and determine the most effective NPK fertilizer rates and potato varieties, a field experiment was conducted in Surma rural municipality of Bajhang district. The experiment utilized a randomized complete block design (RCBD) with three replications, to evaluate the effects of four NPK fertilizer rates (0:0:0, 50:50:50, 100:100:60, and 150:150:90 kg NPK/ha) and three potato varieties (Khumal Seto, Cardinal, and Bajhang Local), on growth, yield, and economic profitability. Statistical analysis, including analysis of variance and Duncan's multiple range test (DMRT), indicated that the highest values for plant height, canopy diameter, number of leaves, number of main stems, tuber weight, fresh weight of leaves and stems, average tuber diameter and number of marketable tubers per hill were consistently observed higher in either the Khumal Seto or Bajhang Local potato varieties. Similarly, these results were particularly prominent with the application of 150:150:90 kg NPK/ha. Economic analysis demonstrated that the Khumal Seto variety showed superior performance in terms of gross benefit, net benefit, and benefit-to-cost ratio (NPR 1,805,714.29, NPR 1,306,168.83, and 3.61, respectively) when compared to other varieties. Similarly, the application of 150:150:90 kg NPK/ha resulted in higher economic returns (NPR 1,645,714.29, NPR 1,129,908.83, and 3.19). In conclusion, using higher levels of mineral fertilizers (150:150:90 kg NPK/ha) with high yielding and well adapted potato varieties such as Khumal Seto and Bajhang Local significantly enhances growth, yield, and profitability in potato cultivation, as demonstrated by the findings of this study.

Optimizing Slow-Release Fertilizer Rate for Crop and Soil Productivity in Kimchi Cabbage Cropping Systems in the Highlands of Gangwon Province

Slow-release fertilizer (SRF) improves Kimchi cabbage (KC) productivity in the Highlands of Gangwon Province in South Korea; however, optimum rates for the region are not established. This study investigated the optimum and most economical rate of SRF that maximizes KC yield, nutrient uptake and nitrogen use efficiency (NUE) and enhances soil quality in two experiments at the Highland Agriculture Research Institute. Post-harvest soil N (mg kg−1), P2O5 (mg kg−1), K, Ca and Mg (cmolc kg−1), pH (1:5), electrical conductivity (EC; dSm−1) and organic matter (OM; g kg−1) were measured to assess soil quality. Added net returns (ANR) of treatments were evaluated. Recommended N rate (238 kg ha−1) for KC production was the basis for treatment applications. Treatments included no fertilizer control (‘nf’), full N recommendation SRF (SF1), ½ N recommendation SRF (SF0.5), double N recommendation SRF (SF2) and full N recommendation conventional fast fertilizer (FF). Results showed that SF0.5, SF1 and SF2 influenced the highest KC marketable yield in both experiments (66–74 and 42–66 Mg ha−1, respectively). SRF rates between 0.5 and 1 times the N recommendation produced the highest possible linear increases in marketable yield; and the most economical, with ANR &gt; KRW 83 million ha−1 in the first experiment and &gt; KRW 22 million ha−1 in the second. Crop N, P, K, Ca and Mg uptakes were highest among the three SRF rates in both experiments. SF0.5 influenced the highest (91%) NUE in the first experiment; however, it left 8 mg kg−1 N by the end of this experiment compared to the start-up 27.2 mg kg−1 N. Thus, nutrient mining occurred. Soil N increased between 23 and 135 mg kg−1 by SF 1 and 2 in both experiments. Soil EC spiked to 0.6 dSm−1 from the initial level of 0.2 dSm−1 by SF2 in the first experiment. Soil pH, P2O5, K, Ca and Mg levels post-harvest were comparable among treatments in both experiments. SF0.5, 1 and 2 increased soil OM by 7–16% above pre-experimental levels in the second experiment. In conclusion, SRF rates between 0.5 and 1 for KC produced the maximum corresponding KC yield and were the most economical. SRF rates ≤ 0.5 pose risks of nutrient mining, which could jeopardise native soil fertility. SF1 and 2 improved some soil quality indices (N and OM). However, SF2 potentiates risks of soil salinity and large P losses, and it is less economical. Therefore, for holistic sustainability of the cropping system, the optimum SRF rate should lie between 0.5 and 1 N recommendation.

Response of Malt Barley (&amp;lt;i&amp;gt;Hordeum distichum L.&amp;lt;/i&amp;gt;) to Different Phosphorus Fertilizer Rates and Irrigation Levels Under Furrow Irrigation Methods in South Eastern Ethiopia

Nutrient availability to crops is a function of soil type, moisture condition, environment, crop type, and management and their interaction affects nutrient use efficiencies and crop growth conditions. The objective of this study was to determine the optimum P rate and deficit irrigation level, as well as to identify the interactive effect of nutrient and moisture levels on yield and yield quality malt barley under irrigation in Ormiya region Tiyo district. The experiment was conducted at small plot level for three consecutive years from 2020/21 to 2022/23 G.C. This experiment was conducted at Kulumsa Agricultural Research Center On-Station arranged by split-plot layout with RCBD design by three replications. Irrigation amounts (100%, 75% and 50%) were assigned the main plot and phosphorus fertilizer rates (0, 10, 20, 30 and 40 kg) corresponded to the subplot. The combined effect of irrigation levels and phosphorus fertilizer rate had a significant effect (p &amp;lt; 0.05) on malt barely grain yield, above-ground biomass, thousand kernel weight and water productivity but not on plant height, seeds per spike and protein content. The highest grain yield and above-ground biomass were 3.16 t/ha and 6.77 t/ha obtained from the application of 100% ETc with 30 kg of phosphorus fertilizer. The maximum water productivity (0.97 kg/m&amp;lt;sup&amp;gt;3&amp;lt;/sup&amp;gt;) was observeat the application of 75% ETc with 30 kg of Phosphorus fertilizer while more profitable practice was found at 100% ETc with 30 kg of phosphorus application. The highest protein content (15.57%) was observed at the application of 50% deficit irrigation and the lowest (14.66%) was observed at 100% ETc irrigation application. Applying the optimum amount of irrigation with 30 Kg phosphorus fertilizer gives high grain and above biomass yield and is economically profitable in Tiyo district and agroecologies similar to Tiyo.

On-farm Pre-extension Demonstration of Newly Released Pigeon pea (Cajanus cajan) Technology with Proper Agronomic Practices in Gamo and Konso Zones of Southern Ethiopia

Pigeon pea is widely cultivated by Ethiopian farmers, but its production remains low despite suitable conditions. This is partly due to inadequate demonstration of new pigeon pea varieties with proper agronomic practices. To address this, Arba Minch Agricultural Research Center released a new variety, Ashenafi, which showed promise in adaptation trials. However, its farmer preference and socio-economic benefits were not assessed. Therefore, a pre-extension demonstration of Ashenafi and a local check was conducted in 2024 at Karat Zuria and Boreda districts to improve pigeon pea production. The demonstration covered 20 farmers’ fields and 2 Farmers Training Centers, with 10m x 50m plots for each variety, using a spacing of 1.2m between rows and 0.5m between plants, a seed rate of 3 kg/ha, and a fertilizer rate of 100 kg/ha NPS. Grain yield data and farmer preferences were collected and analyzed. Ashenafi yielded 1,860 kg/ha compared to the local variety's 1,065 kg/ha at Karat Zuria, and 1,785 kg/ha compared to 890 kg/ha at Boreda. Results at the Farmers Training Center were similar. The significant yield gap of 787 kg/ha suggests a need to encourage adoption of the new variety. Ashenafi proved more profitable and was preferred by farmers for its earliness, quick branch emergence, seed size, grain yield, and pod number. Thus, Ashenafi is recommended for wider production with proper agronomic practices.

Differential Effects of Nitrogen and Phosphorus Fertilization Rates and Fertilizer Placement Methods on P Accumulations in Maize.

Crop production in Afghanistan suffers from limited phosphorus (P) availability, which severely hinders national agriculture sustainability. This study hypothesized that deep fertilizer placement could significantly enhance the uptake of immobile P and, thus, tissue P accumulation and crop yield. A two-year pot experiment growing two maize (Zea mays) hybrid cultivars (Xida-789 and Xida-211) was, therefore, conducted to test these hypotheses under three contrasting fertilizer placement methods (broadcast, side band, and deep band). In doing so, P concentrations in both maize tissues and soils were compared at 45, 60, and 115 days after sowing (DAS) under nine combinations of nitrogen (N) and P fertilizer rates (kg ha-1: N112P45, N112P60, N112P75, N150P45, N150P60, N150P75, N187P45, N187P60, N187P75). Results have shown that deep band placement significantly increased P uptake efficiency, leading to greater P concentration and accumulation in maize tissues compared to the other two fertilization methods. This improved P uptake was attributed to several factors associated with deep placement, including reduced P fixation, enhanced root access to P, and moisture availability for P uptake. Additionally, deep band placement combined with higher N application rates (N187 and N150) further enhanced plant P uptake by promoting P availability and utilization mechanisms. Deep band placement also resulted in significantly higher total soil P, Olsen-P, and P use efficiency than broadcast and side band methods, indicating a more efficient P fertilization strategy for maize that can improve growth and yield. This study also found positive correlations between P concentration in plant organs and soil Olsen-P, highlighting the importance of adequate soil P levels for optimal plant growth. Overall, our results have shown that deep band fertilizer placement emerged as a superior strategy for enhancing P uptake efficiency, utilization, and maize productivity compared to broadcast and side band placement. The outcome generated from the deep band fertilization by this greenhouse study can be recommended for field practices to optimize P fertilizer use and improve maize production while minimizing potential environmental P losses associated with broadcast fertilization.

Traditional compost and BSF-biodigested compost in the organic fertilization of ryegrass

The present study is a contribution to evaluate the agronomic potential of two different organic products (cattle effluents, either composted or digested by Black Soldier Fly larvae) as organic fertilizers, through the measurement of production and the photosynthetic activity of ryegrass (Lolium multiflorum L.), growing in a sandy soil, treated with different doses of those products. Within this aim, an experiment was conducted in a semi-controlled greenhouse with ryegrass plants cultivated in pots, with ten treatments: four different treatments of traditionally composted material, four different treatments of biodigested material, a mineral control (using the recommended rate of mineral fertilizer for ryegrass), and a zero control (without any type of fertilization). Under the experimental conditions, the results showed a significant effect of both organic composts over mineral fertilization, with a better performance of the biodigested by black soldier fly larvae. As for the informative capacity of photosynthetic activity data, in assessing the vegetative development of crops, "net assimilation rate" and "water use efficiency" proved to be the most suitable parameters.

Evaluating the effects of the CERES-Rice model to simulate upland rice (Oryza sativa L.) yield under different plant density and nitrogen management strategies in Fogera Plain, Northwest Ethiopia

This study assessed the optimal nitrogen (N) fertilizer rate and planting density for the well-adapted upland rice cultivar NERICA_4 on the Fogera Plain. The primary objective was to evaluate the effects of varied planting densities and N-fertilizer rates on upland rice yield and other agronomic parameters. A two-year field study (2020 and 2021) was conducted at the Fogera Rice Research Field Station, testing nine plant densities (75, 87, and 98; 72, 82, and 91; 70, 79, and 89 plants per m2 and two N rates (115 and 138 kg N ha−1). The Crop Simulation Model Crop Environment Resource Synthesis (CSM-CERES-Rice) within the Decision Support System for Agrotechnology Transfer (DSSAT) framework was calibrated and validated using site-specific weather, soil, crop, and agronomic management data from the experiment. Results on the subsequent RMSE, RMSEn, and d index values during the calibration phase were 0.074 t ha−1, 1.82 %, and 0.86 of grain yield; 0.307 t ha−1, 3.36 %, and 0.87 of by-product yield; 0.489 t ha−1, 3.74 %, and 0.79 of top dry biomass yield; and 0.28, 8.24 %, and 0.63 of leaf area index values, respectively. Whereas results on the corresponding RMSE, RMSEn, and d index values during the evaluation phase were: 0.58 t ha−1, 1.33 %, and 0.90 of grain yield; 0.69 t ha−1, 0.58 %, and 0.99 of by-product yield; 0.678 t ha−1, 4.36 %, and 0.67 of top dry biomass yield; and 0.75, 13.92 %, and 0.74 of leaf area index, respectively. The findings of the long-term simulation showed that a 23 % increase in grain yield was achieved with 138 kg N ha−1 and 87 plants per m2 of planting density, as compared to 115 kg N ha−1 and 75 plants per m2 of plant density. The recommended optimum plant density and N fertilizer rate were 138 kg N ha−1 with PD2 of plant density for upland rice production in the Fogera Plain.

Effects of eco-green and inorganic nitrogen fertilizer rates on growth and green pod yield of hot pepper (Capsicum annum L.) in Bahir Dar Zuria District of Amhara Region, Ethiopia

Hot pepper (Capsicum annum L.) is one of the most important vegetable crops produced in Ethiopia. However, production and productivity of the crop is far below the world average, which is mostly associated with soil fertility depletions as a result of inappropriate application of fertilizer. Therefore, this field experiment was conducted to evaluate the effects of organic eco-green and inorganic nitrogen fertilizer on the growth and green pod yield of hot pepper during the growing season of 2019/2020. The experiment was designed in factorial combinations of four levels of N (0, 59, 82 and 105 kg ha−1) and four levels of eco-green (0, 75, 125 and 175 L ha−1) which were laid down in Randomized Complete Block Design (RCBD) with three replications. Results revealed that application of N and eco-green (EG) fertilizers very highly significantly (P < 0.001) influenced plant height, numbers of different levels of branches, days to 50% flowering, days to 50% pod setting, days to first harvest, marketable, unmarketable and total green pod yields. Generally, the combination of high levels of nitrogen and EG increased the growth parameters of hot pepper including plant height and number of branches. The highest marketable (17.98 t ha−1) and total green pod yield (18.19 t ha−1) of hot pepper were recorded from the treatment combinations of 59 kg N ha−1 and 125 litter EG ha−1. The same treatment combination had also recorded the highest net benefit (318,516.91 ETB ha−1) with acceptable marginal rate of return (1706%) which can be recommended for economical production of green hot pepper in the study area and areas with similar agro-ecology.

Effects of Nitrogen Fertilizer and Planting Density on Growth, Nutrient Characteristics, and Chlorophyll Fluorescence in Silage Maize

The optimal combination of the nitrogen fertilizer application and planting density with reference to the silage maize yield and quality remains unclear. We hypothesized that increasing both would increase yields following the law of diminishing returns. Yayu26, a silage maize cultivar, was used in a split-plot experiment to investigate the effects of nitrogen fertilizer and planting density on growth, nutrient characteristics, and chlorophyll fluorescence. The main plots were assigned to three planting densities: 60,000 (A1), 75,000 (A2), and 90,000 (A3) plants hm−2, and the subplots were assigned to four nitrogen fertilizer rates: 0 (B1), 120 (B2), 240 (B3), and 360 (B4) kg hm−2. The results showed that increasing the nitrogen application rate and planting density both enhanced silage maize yield. Nitrogen accumulation and agronomic use efficiency peaked at a planting density of 75,000 hm−2. Structural equation modeling showed that the nitrogen application rate and planting density affected nitrogen accumulation and nutrient properties by influencing chlorophyll fluorescence parameters and nitrogen agronomic efficiency, ultimately resulting in a positive effect on the yield. The A3 × B2 treatments exhibited higher nitrogen accumulation, potentially compensating for any deficiencies in the dry-matter yield. Therefore, the A3 × B2 treatment was evaluated as the optimal treatment to achieve sustainable and economically feasible silage maize production.

Effect of coffee husk biochar and inorganic NP fertilizer on soil properties, growth and yield of potato (Solanum tuberosum L.) on acidic soil of southwest Ethiopia

Soil acidity and low soil fertility due to nutrient leaching coupled with low inorganic fertilizer usage is a major cause of low crop yields across Southwest Ethiopia. Recently, biochar potential to improve soil fertility has gained significant attention but there are limited studies on the use of biochar in combination with inorganic fertilizers. A field experiment was, therefore, conducted to investigate the effect of combined application of biochar and inorganic NP nutrient on soil physicochemical properties, growth and yield of potato in Andiracha district, Southwestern Ethiopia. The experiment was laid out in randomized complete block design (RCBD) and replicated three times. The treatment consisted of four levels of biochar rates (0, 2.5, 5 and 7.5 t ha−1) and four fertilizer rates of (0, 75,100 and 125% of recommended N P rates). Data were analyzed using SAS version 9.3 Software. Analysis of variance showed that combined application of biochar and inorganic NP fertilizer had highly significant (p < 0.01) effect on days to flowering, stem number, plant height, total leaf area, total dry biomass, marketable tuber number per hill and harvest index and significant (p < 0.05) effect on marketable tuber weight and total tuber weight ha−1. Combined application of 7.5 ton ha−1 biochar with 165 kg N and 60 kg P ha−1 resulted highest tuber yield (42.64 t ha−1), that increased yield by 28.99% compared with recommended NP fertilizer alone (165 kg N ha−1 and 60 kg P ha−1), and by 76.6% compared to the control. The increase was mainly attributed to the improvement in soil physico-chemical properties especially soil pH, CEC, organic matter, total N and available P which is a reflection of increase in soil fertility. Consequently, it was determined that the best course of action for potato production in the area was to apply 7.5 tons of biochar ha−1 together with 165 kg N and 60 kg P ha−1. Therefore, the study recommends adoption of low cost biochar production techniques and capacity building to ensure satisfactory knowledge of biochar use and its adoption by potato growers for soil fertility management and enhanced crop productivity.