Low Soil Fertility Research Articles

Agronomic Practices Adopted by the Maize (Zea mays) Farmers in Horowpathana DS Division in Anuradhapura, Sri Lanka

Maize (Zea mays L.) is the third most important cereal crop globally and a vital crop in Sri Lanka, particularly in the Dry and Intermediate zones. This survey was conducted to assess the major challenges faced by maize farmers and the agronomic practices they adopt in the Horowpathana area of the Anuradhapura District, Sri Lanka. A total of 60 farmers from 12 Grama Niladhari (GN) divisions were randomly selected for the study. Data were collected through a questionnaire survey, and descriptive and inferential statistical analyses were performed. The findings revealed that the majority of maize farmers were aged between 36 and 40 years, with both men and women engaged in cultivation. The majority of farmers were educated, yet a significant proportion did not use organic fertilizers, relying primarily on chemical fertilizers. Herbicide use was common, with all farmers applying it to control weeds after planting maize. The study identified several challenges faced by farmers, including adverse weather conditions such as drying and high winds, which were reported by 18.3% of the farmers. Strong winds were found to cause significant damage to maize plants, particularly during the rainy season. Additionally, farmers experienced financial constraints, spending significant amounts on land preparation, chemicals, seeds, labor, transportation, and harvesting, leading to a low-income economy. Price fluctuations of maize grain, lack of storage facilities, and high transportation costs were also major issues affecting the marketing of maize. Biotic and abiotic constraints, such as weeds, drought, low soil fertility, and high input costs, were identified as key factors limiting production. The study concluded that most farmers did not adhere to recommended management practices, resulting in severe yield losses. Therefore, it is crucial to implement awareness programs to encourage proper management practices, ensuring the sustainability of maize production and safeguarding the local economy.

PERFORMANCE OF GROUNDNUT (Arachis hypogaea L.) VARIETIES AS INFLUENCED BY PHOSPHORUS AND MULCHING IN THE NIGERIA SAVANNA

The study on groundnut (Arachis hypogaea L.) performance under different rates of phosphorus and mulching in the Nigeria savannas addresses challenges of low soil fertility and harsh climatic conditions. Groundnut, an important crop in Nigeria, is limited by phosphorus deficiency and soil moisture stress in the savannas. Phosphorus is vital for root development, flowering, and seed production but is often deficient in the region’s alkaline soils. Mulching helps conserve moisture, reduce erosion, and improve fertility by adding organic matter. Identifying optimal combinations of phosphorus and mulching can enhance groundnut yield and sustainability. Field trials were conducted at the Irrigation Research Farms of the Institute for Agricultural Research, Samaru and Kadawa in dry season of 2024 to evaluate two varieties of groundnut (SAMNUT-24 and SAMNUT-25), three phosphorus rates 0, 30 and 60 kgP205ha-1), and three mulch materials (no mulch, polythene sheet and rice straw). Treatments were laid out in a randomized complete block design with three replications. Results showed SAMNUT-24 excelled in branches, canopy spread and shoots dry weight, while SAMNUT-25 produced higher pod yield and harvest index. Applying 60 kgP205 ha-1 improved leaves, pod yield and harvest index, while polythene sheets enhanced leaf number and canopy spread. Both varieties performed well under irrigation. SAMNUT-24 and SAMNUT-25 with 60 kgP2O5ha-1 and rice straw mulch is recommended for farmers. Further research is needed to explore phosphorus rates with new/improved varieties.

Soil fertility management on sesame (Sesamum indicum L.) production in Northern Ethiopia: A review.

Sesame (Sesamum indicum L.) is an important cash crop and plays a vital role in many people's livelihoods in Ethiopia. However, its production is low due to many constraints, and low soil fertility is among the major. The previous fertilizer recommendation was a blanket recommendation regardless of the soil fertility status. Hence, the objective of this review is to synthesize the different recommendations and forward to the sesame growing areas. R statistical software and Python programming language used to analyze the chemical and physical soil properties, association among the chemical and physical soil properties and association with soil depth. The organic carbon, total N (Nitrogen), available P (Phosphorus), S (Sulfur) and Zn (Zinc) are below optimum value while K is sufficient in the soil and moderately alkaline soil. The soil particle size is dominantly clay (58.5%). The clay particle size and pH increased while the sand and silt particle sizes, organic carbon, total N, available P and S decreased as the soil depth increased. 204,558.8 ton of sesame stack residue are burned every year, and from this, 7360.03 ton of NPK is lost every year in Western Tigray. The recommended N, P and S for sesame are: (i) 64 and 41kgha -1N for low N content areas and for medium N content areas respectively; 46 and 23kgha -1 P2O5 for low and medium P content areas; (iii) 60 and 30kgha -1S for low medium S content areas may be recommended to boost sesame production.

An assessment of plant growth and physiological responses in annual crops grown in P deficient soils inoculated with indigenous arbuscular mycorrhizal fungi.

The influence of arbuscular mycorrhizal fungi (AMF) inoculation on the growth and physiology of Phaseolus vulgaris L. and Zea mays L. in the Brazilian tropical seasonal dry forest is not well known. We examined the effects of indigenous AMF species inoculation on these two annual crops at phosphorus-deficient soils under glasshouse conditions. The AMF species used as inoculum were collected from the root zone of Mimosa tenuiflora, a native plant of the Caatinga ecoregion. The inoculum was propagated in plastic pots with Trifolium sp. as the host plant. We investigated the effect of four treatments: (1) Control- non-inoculated; (2) Acaulospora inoculum- inoculation with A. tuberculata; (3) Gigaspora inoculum- inoculation with G. gigantea; and (4) Mixed inoculum- inoculation with both Acaulospora and Gigaspora species. We found that inoculation with the indigenous AMF community enhanced plant dry biomass, plant P concentration, root colonization, and physiological responses for both model plants. This study highlighted the importance of exploring the P molecule as an integral element in plant development and presents the AMF inoculation as an efficient alternative to overcome low-P conditions, leading to improved nutrient acquisition in low-fertility soils, better growth conditions through enhanced physiological responses, and ultimately increased plant dry biomass.

Equine Manure Composition, Soil Fertility and Forage Response

ABSTRACT This study determined the nutrient composition of horse manure and examined the agronomic implications of applying it to pastureland. Horse manure and wood shavings bedding mix obtained from diverse equine operations was sampled from 20 truckloads (~150 m3). Manure was applied once at 817 m3 ha−1 onto replicated bovine pasture plots and compared for forage yield, soil fertility levels and weeds species, with unamended plots over a five-year period. On average, the manure had a carbon to nitrogen (C:N) ratio of 32, mean 72% moisture content, and concentrations (g kg−1 dry weight) 17.5 nitrogen (N), 3.4 phosphorus (P), 13 potassium (K), 8.8 calcium (Ca), 3.7 magnesium (Mg), and 2 sulfur (S). Manure application increased soil test levels of P, K, Ca, and zinc (Zn), soil pH, organic matter content, pasture forage yields and clover biomass. Horse manure application increased Horsenettle (Solanum carolinense L.) biomass, while dandelion (Taraxacum officinale F. H. Wigg.), catchweed bedstraw (Galium aparine L.), and broadleaf plantain (Plantago major) biomass decreased. Except for increasing the amount of horsenettle on pastureland, findings demonstrate that horse manure is a valuable agronomic resource when applied to a low fertility soil.

The role of social-psychological factors in the adoption of push-pull technology by small-scale farmers in East Africa: Application of the theory of planned behavior.

Push-pull technology (PPT) continues to gain relevance among smallholder farmers across the East African region in managing the constraints affecting cereal crop yields including stemborers, fall armyworm, striga weed, and low soil fertility. While previous research has emphasized the significance of socioeconomic factors in explaining farmers' decisions to adopt PPT, the social-psychological factors that influence farmers' adoption intentions have not been extensively studied. Therefore, this study investigated the influence of social-psychological factors on the intention to adopt or increase the land area under PPT based on the theory of planned behavior (TPB). Moreover, this study extends the applicability of the TPB by incorporating an additional construct that addresses practical limitations within adoption decision-making, and providing evidence of how TPB constructs function differently across distinct agricultural contexts. Nine hundred and seventy-one (971) cereal growers comprising PPT users and non-users were interviewed in Kenya, Uganda, Tanzania, and Rwanda using a structured questionnaire. Utilizing the Partial Least Square-Structural Equation Modelling (PLS-SEM) and Artificial Neural Network (ANN), this study revealed a significant positive influence of TPB conceptual elements attitudes, subjective norms, and perceived behavioral control on farmers' intentions to adopt or expand the land area under PPT. Additionally, the study found that the added construct "perceived limitations" negatively impacts these intentions. The results indicated significant variations in the impact of TPB constructs on the intentions to adopt and expand land under PPT across the studied countries. These insights underscore the need for tailored, context-sensitive interventions that integrate behavioral, social, and practical considerations. Additionally, understanding the country-specific determinants allows for more targeted policy measures, extension services, and support programs that can enhance the adoption and effectiveness of PPT, ultimately improving agricultural outcomes and livelihoods of farmers in this region.

Evaluation of Legume Cover Crop Species for Citrus Production in Southeast Florida

Because of the low fertility soils native to southeast Florida and the high nutrient demand of citrus trees under citrus greening—an endemic bacterial disease impacting nutrient uptake—growers are returning to the use of cover crops to improve soil fertility. Cover crops, specifically legumes, can improve soil nitrogen (N) availability because of their ability to fix N from the atmosphere. More citrus growers in southeast Florida are growing cover crops; however, there is a lack of recent research of suitable legume species and their impact on soil N cycling. To address this gap in the literature, six different treatments consisting of five legume species monocultures and one fallow plot (control) were organized into a completely randomized design. The experiment was conducted twice under warm and cool season conditions, and each treatment was replicated five times (n = 5), for a total of 30 experimental plots. Legume species were hairy indigo (Indigofera hirsuta), sunn hemp (Crotalaria juncea), cowpea (Vigna unguiculata), alfalfa (Medicago sativa), and aeschynomene (Aeschynomene americana). Biomass production, N concentration, and nodule characteristics as well as their impact on soil N were measured over a 1-year span in both warm and cool seasons. Overall, both cowpea and hairy indigo produced more biomass and, as a result, higher tissue N compared with those of the other legumes at both 60 and 150 days after planting. However, no impact on soil N was observed. Additionally, all legumes were unable to survive in the cool season, resulting in no measurable biomass at 150 days after planting. These results are relevant for citrus growers aiming to enhance soil fertility through cover crops in southeast Florida. While several legume options are available for the warm season (e.g., cowpea, hairy indigo, and sunn hemp), suitable legume species for the cool season have yet to be identified.

Integrating vermicompost, black soldier fly, and inorganic fertilizers enhances corn growth and yield.

To achieve good agricultural practices and maximize the economic yield of corn, farmers should reduce the use of inorganic fertilizers. A field experiment was conducted in the Chonnabot district, Khon Kaen province, Thailand, during the 2022 and 2023 growing seasons. The aim was to assess the impact of different organic fertilizers and their combinations on the growth and yield of commercial sweet corn (Zea mays L. saccharata) and waxy corn (Zea mays L. var. ceratina) hybrids. The results showed that sweet corn had significantly higher ear fresh weight, protein, fat, and fiber content compared to waxy corn, with values of 7,529.20kgha-1, 14.48%, 4.74%, and 1.30%, respectively. Two treatments, F4 (190.63kgNha-1+46.88kgPha-1+46.88kgKha-1) and F3 (6,250kgha-1 of black soldier fly (BSF)+95.31kgNha-1+23.44kgPha-1+23.44kgKha-1) resulted in the highest ear fresh weight, with 6,569.90 and 6,275.40kgha-1, respectively. In contrast, F4 showed higher protein (12.04%), fat (4.62%), and fiber content (0.91%) than F3. Significant improvements were observed in SPAD value, biomass, and yield parameters. Corn plants treated with a combination of vermicompost, BSF, and inorganic fertilizer showed higher ear length, ear diameter, ear fresh weight, and dry biomass than control plants (no fertilizer management, F1). The F1 treatment led to higher carbohydrate content in both corn cultivars tested, with a notable impact on pink waxy corn (82.06%). Our findings suggest that using a combination of BSF and inorganic fertilizers is promising for reducing the use of inorganic fertilizers and providing the highest net income among the three fresh corn cultivars. Pink waxy corn showed greater adaptability under low soil fertility conditions owing to better yield components than purple waxy corn when evaluated without fertilizers.

From chocolate to palm oil: The future of Indonesia's cocoa plantations.

Indonesia is the world's third largest cocoa producer, but production is decreasing since 2011. We revisited cocoa farmers for an environmental assessment in Luwu Timur, Sulawesi, 7months after a socio-economic survey on cocoa certification outcomes and observed many cocoa plantations being converted into oil palm and maize. Including our field data as well as secondary data on commodity prices and yields, we outline reasons for cocoa conversion, potential consequences for biodiversity, and assess the future outlook for the Indonesian cocoa sector. Low cocoa productivity, volatile cocoa prices and higher revenue for oil palm, among others, drive land-use change. If shade trees are cut during cocoa conversion, it may have negative implications for biodiversity. Solutions to low soil fertility, omnipresent pests and diseases, and stable producer prices are needed to increase profitability of cocoa and prevent conversion of cocoa agroforests to oil palm monocultures.

EVALUASI STATUS KESUBURAN TANAH ULTISOL PADA DUA PENGGUNAAN LAHAN DI DESA PAK BULU KECAMATAN ANJONGAN KABUPATEN MEMPAWAH

Ultisols generally have low soil fertility status due to their acidic nature, low organic matter, and limited nutrient availability. The utilization of ultisols for oil palm plantations and secondary forests certainly affects the availability of nutrients, organic matter, and soil acidity. Soil management that does not align with the fertility conditions will result in other problems that can threaten the sustainability of agricultural production. The lack of comprehensive research on soil fertility, particularly in Pak Bulu Village, Anjongan Sub-District, limits the available information on the long-term impacts that could affect soil quality. This situation highlights the importance of conducting this research to determine the appropriate land management practices for soil fertility in each land use. This study employed a soil survey method, with sampling points determined by overlaying maps of soil types, slope classes, and land use, using a purposive sampling method, which was divided into four land units. The soil samples were analyzed for their chemical properties in the Soil Chemistry and Fertility Laboratory of the Faculty of Agriculture, Tanjungpura University. The laboratory results were then categorized based on the criteria for evaluating soil chemical properties by the Soil Research Center (1983), and the soil fertility status was subsequently evaluated based on the soil fertility evaluation guidelines by the Soil Research Center Bogor (1995). The evaluation results showed that the soil fertility status of both land uses was at the same level; however, the oil palm plantation had limiting factors such as Cation Exchange Capacity (CEC), Base Saturation (BS), Total Phosphorus (P-total), and Total Potassium (K-total) that were classified as low to very low, while the secondary forest only had Base Saturation and Total Potassium classified as very low, with CEC classified as low.

Respon Cabai Rawit (Capsicum frutescens L.) Terhadap Pupuk Organik Cair Berbahan Lindi pada Lahan Marginal

Coastal land is identical to marginal land, namely having a low soil fertility level. Liquid organic fertilizer (LOF) made from leachate can be used to increase the availability of nutrients in the soil. This study focuses on increasing the growth and yield of cayenne pepper plants on marginal land using various doses of liquid organik fertilizer made from leachate. This study was conducted from May to September 2023. The treatment was the provision of LOF consisting of 4, namely without LOF, 20%, 40%, and 60%. The results of the study showed that the liquid organic fertilizer treatment was able to increase nutrients in the soil. Treatment without liquid organic fertilizer and 60% liquid organik fertilizer significantly affected plant height. Meanwhile, the treatment without liquid organic fertilizer and 20% liquid organic fertilizer was significant for stem diameter, number of fruits, and fruit weight of cayenne pepper plants. The 20% liquid organik fertilizer treatment is recommended to increase the growth and yield of cayenne pepper plants.

Influence of Date of Sowing and Boron Fertilization on Incidence of Yellow Vein Mosaic Virus in Kharif Okra, Abelmoschus esculentus

Background: Okra requires a long period of warm and humid weather. It may be cultivated effectively in hot, humid climates. It is susceptible to frost and very low temperatures. Temperatures between 24°C to 28°C are considered ideal for regular growth and development. Aim: The experiment was carrying the objective of establishment the relationship between incidence of YVMV and weather parameters during growing season of okra and to access the relation between YVMV incidence and boron application. Methodology: A field experiment was conducted at farmer’s field at Andharua Bhubaneswar with Okra (cv-lily) as test crop at two dates of sowing i.e., 30th January (D1) and 15th February 2021 (D2) with 10 boron treatments comprising of B-0, b-1.5kg/ha soil, 0.25%, 0.5%, 0.75%, 1.0% borax once and twice foliar spray in a low boron (0.35 mg/kg) and low fertile acidic soil. The crop experienced 109.7mm rainfall, 10 rainy days, 29.1°C-39.9°C Tmax, 13.2°C-27.3°C Tmin.The BSH was 2.7-8.1 hrs. Results: The emergence count, plant height, plant population and leaf area were better in D2. The fresh fruit yield of Okra varied from 6.52-9.15 t/ha where D2 produced more than D1. The boron content of fruit varied from 0.09 to 0.18mg/kg where T8 contain more boron. The YVMV PDI attend the peak 12.59-29.62 during the 2nd week of April at 77 DAS in D1(first date of sowing. Similarly in D2 (second date of sowing, the peak was attended at 63 DAS i.e., the 3rd week of April varied from 11.85-29.62%. From this experiment, out of seven weather parameters, Tmin and Evaporation have got the higher contributing factor for the incidence of YVMV. The D1 experiences prolonged favourable weather condition for YVMV incidence compared to D2. Conclusion: Twice foliar spray or soil application of boron reduced the severity of YVMV to a greater extent compared to no or once application among different concentrations @ 0.5% borax was the most suitable dose for Okra crop in the east and south-east coastal plain zone of Odisha.

Counseling of How to Make Organic Fertilizer Enriched with Phosphate Solubilizing Bacteria to the Community in Tanjung Raja Sub-District

The village of Talang Balai Baru 1, located in the sub-district of Tanjung Raja in the Ogan Ilir Regency, is characterized by a type of land known as lowland, locally called “lebak” land, which is characterized by low soil fertility. This factor, among others, contributes to a decrease in crop productivity. To address this challenge, it is imperative to employ organic fertilizer in optimal amounts. Specifically, the harvested straw is primarily incinerated, with a limited portion being utilized as chicken manure fertilizer. Despite the abundance of local resources like chicken manure and straw, they are underutilized. Therefore, there is a need to harness these resources for the production of organic fertilizers enriched with phosphate-solubilizing bacteria (PSB). This enriched organic fertilizer is expected to provide essential nutrients to plants and improve soil fertility, thereby boosting soil and crop productivity. The project, conducted from July 29, 2024, to August 27, 2024. The method employed in this study is counseling and socialization regarding the production of BPF-enriched organic fertilizer and its subsequent application by partner farmers. The results of this counseling and socialization demonstrate the high level of support among the residents of Talang Balai Baru 1 Village for this program, as evidenced by their ability to utilize BPF-enriched organic fertilizer on their respective fields. This will contribute to an enhancement in soil and plant productivity.

The effect of mycorrhiza-inoculated succession-planted main crop (maize-wheat) and cover crop rotation on soil organic carbon

There has long been intense pressure on input-based traditional agriculture due to the rising need for food. These kinds of agricultural techniques result in poorly managed soil-plant interactions that ultimately affect all living activities and human health by altering and destroying the soil's natural structure, rendering it infertile, and degrading soil quality. Research was carried out a study to find out how mycorrhizae-inoculated cover crops affected soil quality and growth metrics. The study to pot experiment was carried out under greenhouse conditions. Five different plant combinations (cover crop) patterns were inoculated with selected and indigenous mycorrhizae spores that were isolated from the rhizosphere soils of plants grown in three degraded soils. Five different cover plant combinations, such as A: Clover, Grass, Onion; B: Faba Bean, Grass, Safflower; C: Clover, Grass, Safflower, Faba Bean, Onion; D: Maize; and E: Wheat, were planted in 7 kg soil-containing pots with three replications. The seeds of different plants were planted per m2 surface of each pot, with the number of seeds per pot calculated depending on their sowing amount per hectare. Sixty days after planting, the plants were harvested by cutting 0.5 cm above the soil surface with scissors. In the second rotation experiment, after the harvest of the first rotation experiment, maize (Zea mays L.) was planted on the A, B, C, and D patterns, and wheat was planted on the E pattern. In the third rotation, wheat was sown on all pots after the second maize harvest. As a result of successive three-pot experiments on the same soils, were analyzed for the soil organic carbon (SOC) concentrations. In general, treatments with Funneliformis mosseae followed by indigenous mycorrhiza spores led to an increase in soil OC concentration compared to control treatments. SOC concentrations in Havutlu and Arık soils were higher than those in Avadan soil. Avadan is a highly eroded soil and has high lime content, high pH, and low soil fertility. When consecutively planted trials are examined, the soil SOC concentration increased from the first trial to the last trial for all soils. The obtained SOC results seem to partially support the research hypothesis. The results revealed that poorly managed soil requires rehabilitations with various combinations of cover crops.

Survival of 13 Forage Legumes in Contrasting Environments of Central Otago, New Zealand

ABSTRACTThe lack of suitable perennial and annual forage legumes strongly constrains the productivity and sustainability of upland grasslands in New Zealand. Legumes support sustainable grassland production through nitrogen fixation and increased yields. However, traditional legume species such as white clover (Trifolium repens L.) struggle to persist within New Zealand's upland climatic and edaphic conditions characterised by acid, low fertility soils and short growing seasons. To address this challenge, we assessed the survival of 13 forage legume species over 2 years at three field sites across Central Otago, capturing the districts varied precipitation and temperature profiles. Legume survival rates, biomass and weather data were measured. Notably, lotus (Lotus pedunculatus Cav.) exhibited 100% survival over the 2 years on high altitude acidic, low fertility soils, whereas other perennial legume species showed limited persistence (0%–55% survival) and low biomass production. Crimson clover (Trifolium incarnatum L.) had the greatest Year 1 establishment and biomass of annual legumes species at low and medium rainfall sites. Moreover, strong Year 1 seed set and subsequent regeneration in Year 2 were observed for crimson clover, striated clover (Trifolium striatum L.), and subterranean clover (Trifolium subterraneum L.) (cvs. Denmark and Narrikup). These findings underscore the potential of these annual legume species in dryland environments due to their regeneration capacity before summer drought onset. Climate emerged as a pivotal determinant influencing the viability of less resilient species across all trial locations. Lotus and crimson clover are alternative legume species with the potential to enhance sustainable grassland productivity in New Zealand's upland farming systems.

EVALUASI STATUS KESUBURAN TANAH PADA BEBERAPA JENIS PENGGUNAAN LAHAN DI DESA PENGERAGOAN, KECAMATAN PEKUTATAN, KABUPATEN JEMBRANA

This research was carried out in Pengeragoan Village, Pekutatan District, Jembrana Regency, from July to September 2023. The aim of this research was to determine the chemical properties of soil and determine soil fertility status classes and provide direction in land management according to the level of soil fertility status for each type. Land use in Pengeragoan Village, Pekutatan District, Jembrana Regency. The types of land use that exist include coffee plantations, cocoa plantations, coconut plantations, mixed plantations, natural forests, teak forests and rice fields. Sampling was carried out compositely on several existing land use types, namely coffee plantations (Tki), cocoa plantations (Tko), coconut plantations (Tka), mixed plantations (Tc), natural forests (Tha), teak forests (Tj), and rice field (Ts). Determination of soil fertility status is carried out by measuring soil chemical properties parameters, namely soil Cation Exchange Capacity (CEC), Base Saturation (KB), P-total, K-total and C-organic. The research results show that the soil fertility status in several types of land use falls into the criteria of high, medium and low. Natural forest and mixed garden land use types have high soil fertility status. The land use types of coffee plantations, cocoa plantations and teak forests have medium soil fertility status. The land use types of coconut plantations and rice fields have low soil fertility status. The management direction recommended from the results of evaluating soil fertility status and several supporting soil chemical properties for each type of land use is the need to add N and P nutrients to the land use types of coffee plantations, mixed plantations and natural forests. In the types of land use of cocoa plantations, coconut plantations, teak forests and rice fields, it is necessary to add nutrients N, P and organic materials in the form of plant litter and organic fertilizer.

Revealing molecular adaptive response in maize (Zea mays L.) under nitrogen starvation stress in low fertile sandy soil

Revealing molecular adaptive response in maize (Zea mays L.) under nitrogen starvation stress in low fertile sandy soil

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.

Haricot Bean (<i>Phaseolus vulgaris</i> L.) Varieties Adaptation Trial in Buno Bedele and Ilu Ababor Zones, South West Oromia

Haricot bean is one of the most economically important pulse crops cultivated in Ethiopia. However, its average yield reported at national level remains far below the potential yield to be attained. This is partly due to low soil fertility management, inappropriate agronomic packages and diseases and pest problems and lack of improved varieties. Hence, this experiment was conducted with the objectives of to test the performance of released improved Haricot bean varieties on yield and yield related components and Insect and disease resistant varieties for the study at Western parts of Oromia. The experiment was conducted in Buno Bedele (D/Hana) and Ilu Ababor (Bure) districts during 2020 to 2021 cropping season. Nine (9) improved Haricot bean varieties were used as testing materials. The experimental design was RCBD with three replications. Data were collected on six quantitative morphological traits like days to 50% flowering, days to maturity, number of seed per pod, pod length and grain yields. Analyses of data revealed significant varietal differences (P<0.05) in grain yield, days to 50% flowering, days to 95% maturity, seed per pod and for plant height. However, no significant varietal differences were observed in Number of pods per plant. SER 119 and SER 125 varieties were significantly yielder than the rest and recommended as promising variety under the study area. Therefore, these two varieties are recommended for demonstration and further scaling up.

Effects of exogenous nitrogen addition on soil organic nitrogen fractions in different fertility soils: Result from a 15N cross-labeling experiment

Exogenous nitrogen (N) addition serves as a pivotal nutrient management strategy, significantly enhancing agricultural production by regulating soil N availability and retention. However, the dynamics of soil organic nitrogen (SON) fractions in response to various forms of exogenous N addition across differing soil fertility levels remain inadequately understood. This study utilized data from a 25-year fertilization experiment and a 15N cross-labeling experiment in Northeast China to assess and quantify the effects of mineral N fertilizers and organic materials (manure and straw) on SON fractions in NPK (mineral fertilizer addition) and NPKM (NPK combined with composted pig manure) treatments. Our findings indicate that long-term incorporation of manure substantially elevates soil fertility compared to the exclusive use of mineral fertilizers. Notably, exogenous N primarily boosts soil N availability by enhancing acid-soluble organic N fractions, particularly ammonium nitrogen (AN) and amino acid nitrogen (AAN). Organic materials, particularly straw, significantly enhanced the retention of mineral fertilizer N in both NPK and NPKM treatments (9.54 % vs 10.70 %). Moreover, over 70 % of the N from straw or manure remained in the soil as stable SON fractions. While straw rapidly improves low-fertility soils, manure contributes to enhanced soil N reserves and increased crop yields. Therefore, incorporating organic matter may bolster soil N sequestration in Northeast China, which is contingent upon soil fertility and tailored fertilizer management strategies. This research elucidates the distribution and conversion of exogenous N within SON pools, facilitating optimized N management, sustaining yields, reducing farmland N pollution, and promoting agricultural sustainability.