![The particle size distribution of the soil is clay with (3% sand, 10% silt and 87% clay). The soil pH was 7.4-7.8 which is slightly alkaline [46]. Lentil has been found to do well at pH values of 7.61 however; lentils grow best at a soil pH of 6.0 to 8.0 so that the soil pH is ideal for lentil production. The soil organic carbon content was 1.53%. Similarly, total nitrogen of 0.04%, CEC of 26.67 cmol (+) kg™!and total available phosphorus of 45.31 ppm (Table 1). The soil of the experimental site has high organic carbon content, very low total N, medium CEC and high in available P [46] and [47] (Table 1). Table 1: Pre-planting soil physicochemical analysis result of the study area. OM=Organic Matter; TN=Total Nitrogen; TAP=Total Available Phosphorus; CEC=Cation Exchange Capacity.](https://figures.academia-assets.com/112408409/table_001.jpg)
![The application of phosphorus rates beyond 20 kg P ha"! resulted in decreased number of nodule per plant for all the varieties. Similarly, Taylor [61] reported increased number of nodules per plant due to phosphorus application. During nodulation, P is an essential ingredient for Rhizobium bacteria to convert atmospheric N, into an ammonium (NH4*) form usable by plants. Inadequate phosphorus restricts root growth, the process of photosynthesis, translocation of sugars and other such functions which directly influence N fixation by legume plants. Similarly, phosphorus fertilizer application was reported to significantly enhanced nodule number in cowpea [55]. Rahman [62] also reported that varieties significantly affect the growth, development and yield of lentil. Table 3B: Interaction effect of phosphorus rates and varieties on number of nodules per plant of lentil at Ambo in 2016. Means within the same column followed by the same letter are not significantly different at 5% probability level. LSD: Least Significant Difference; CV: Coefficient of Variation.](https://figures.academia-assets.com/112408409/table_005.jpg)
![P ha” gave significantly taller plants to other P rates for all the varieties (Table 4). Increased in plant height with the increase in rate of P might be due to phosphorus fertilizer contribution to availability of soil nutrients which increases their uptake by plants. Likewise, Tekle [16] described that phosphorus application that facilitated better absorption of soil moisture and nutrients resulting in taller plant height of faba bean in comparison with no phosphorus application. Table 4: Interaction effect of phosphorus rates and varieties on plant height of Lentil at Ambo in 2016. Means within the same column](https://figures.academia-assets.com/112408409/table_006.jpg)
![rroducvion The highest net benefit of EB 72240 ha"! with marginal rate of return of 1177% was obtained with application of 20kg P ha‘! followed by net benefit of EB 62706 ha! and marginal rate return of 1445% with application of 10 kg P ha‘! and the lower net benefit was 55188 EB ha"! with marginal rate return 243% through application of 30kg P ha*!(Table 10). This is agreement with the findings of [58]. Therefore, application of 20 kg P ha! is economical feasible for lentil production in Ambo area which support the previous P fertilizer recommendation for pulses in the country. Adv Crop Sci Tech, an open access journal ISSN: 2329-8863](https://figures.academia-assets.com/112408409/table_013.jpg)
![Table 1. Number of pods per plant, thousand grain weight and grain yield of lentil as influenced by different levels of phosphorus and zinc application of phosphorus at the rate of 40 kg ha''resulted lowest grain yield (1238.9 kg ha’). The reason for increasing grain yield is the balance nutrient supply and timely application of the nutrients which enhances the plant growth and the grain yield will be increased. Similar results support that increasing phosphorus level, the grain yield increased too [18, 19]. In case of zinc the higher grain yield (1846 kg ha!) was obtained at 9 kg Zn ha! while lowest grain yield (1574 kg ha’!) was recorded at 3 kg Zn ha‘!. Similar results were reported on the grain yield [20-22].](https://figures.academia-assets.com/86960686/table_001.jpg)
![Table 1. Number of pods per plant, thousand grain weight and grain yield of lentil as influenced by different levels of phosphorus and zinc application of phosphorus at the rate of 40 kg ha''resulted lowest grain yield (1238.9 kg ha’). The reason for increasing grain yield is the balance nutrient supply and timely application of the nutrients which enhances the plant growth and the grain yield will be increased. Similar results support that increasing phosphorus level, the grain yield increased too [18, 19]. In case of zinc the higher grain yield (1846 kg ha!) was obtained at 9 kg Zn ha! while lowest grain yield (1574 kg ha’!) was recorded at 3 kg Zn ha‘!. Similar results were reported on the grain yield [20-22].](https://figures.academia-assets.com/81746653/table_001.jpg)
![Fig. 3. Response of maize straw ash treatment on fresh weight This experiment showed that application of maize straw ash as an amendment has positive impacts on yield production of two cultivars of Malabar which was also found by Shi et al.. They found that the application of biomass ash was beneficial to the growth and yield of wheat. Melese and Yli-Halla (2016) investigated that increasing rates of wood ash application significantly increased fresh shoot biomass), Krejs] and Scanlon (1996) observed the significant increase of biomass production of Oats and Beans that were grown in soils treated with ash®). Soil calcareousness causes deficiency of N, P, K, Mg, Z, Cu and Fe which lead to low yield(®. Macronutrient Concentration](https://figures.academia-assets.com/71747550/figure_003.jpg)
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Key research themes
1. How can integrated nutrient management improve soil fertility and plant nutrient availability for sustainable crop production?
This research theme focuses on combining organic and inorganic nutrient sources, managing soil health, and optimizing fertilization strategies to enhance nutrient use efficiency and balance soil fertility. It matters because sustainable agricultural productivity depends on maintaining soil nutrient pools, nutrient cycling, and reducing environmental impacts while meeting crop demands.
Key finding: This study highlights the importance of balanced and integrated fertilizer use combined with organic amendments to improve soil organic matter, microbial activity, and nutrient availability. It provides actionable insights on... Read more
Key finding: The paper introduces the concept of the nitrogen gap (NG) and yield gap (YG) to precisely quantify fertilizer nitrogen inefficiency linked to soil constraints such as compaction and pH. It recommends synchronizing nitrogen... Read more
Key finding: The research elucidates Integrated Soil Fertility Management (ISFM) principles, emphasizing the joint use of mineral fertilizers, organic matter, well-adapted crop germplasm, and good agronomic practices within crop... Read more
Key finding: By experimentally testing varying NPK fertilizer rates over multiple cropping cycles, the study quantifies nutrient depletion and accumulation patterns. It finds that balanced fertilization maintains positive nutrient... Read more
2. What are the roles of soil microbial communities and organic amendments in enhancing nutrient cycling and improving soil quality for plant nutrition?
This theme investigates the microbiological dimension of soil fertility, focusing on how soil organisms, bio-fertilizers, and organic wastes contribute to nutrient availability, soil enzyme activities, and restoration of degraded or contaminated soils. Such biological approaches are crucial for sustainable nutrient supply, improving soil structure, and supporting plant growth.
Key finding: The study demonstrates that organic amendments like sewage sludge can significantly enhance soil fertility and crop biomass without detrimental shifts in nutrient balance. It also illustrates how bio-fertilizers containing... Read more
Key finding: This work shows that agroforestry systems (AFS) improve soil nutrient dynamics, including micronutrient retention, over different soil depths and seasons compared to fallow soils. It links AFS biodiversity to enhanced soil... Read more
Key finding: The research also evaluates the restoration of soil biological activity in pesticide/heavy metal contaminated soils using organic amendments like barley straw versus bentonite, concluding that organic inputs more effectively... Read more
Key finding: This paper integrates soil chemical nutrient data with biological indicators from 118 field samples to reveal spatial variability in macronutrients and micronutrients such as Zn, Mn, Fe, and Cu, emphasizing that micronutrient... Read more
3. How do micronutrient dynamics and soil chemical properties affect plant growth and nutritional quality in diverse cropping systems and soil types?
This theme centers on the distribution, availability, and fertilization of micro- and macronutrients in different soil types, including calcareous and acidic soils, as well as their uptake by crops influencing yield and quality. It involves quantifying nutrient deficiencies, evaluating response to targeted fertilization (e.g., Zn, K), and addressing soil chemical constraints affecting crop nutrition.
Key finding: The research maps the status of essential macronutrients and micronutrients (Zn, Cu, Mn, Fe, B) and finds availability significantly influenced by soil pH, organic carbon, and exchangeable bases. The positive correlations... Read more
Key finding: By assessing six lentil varieties under 0 and 2 kg Zn ha-1, this study demonstrates significant improvements in seed yield, Zn content, and protein content due to Zn fertilization on zinc-deficient calcareous and terrace... Read more
Key finding: This two-year study quantifies the response of lentil to increasing potassium rates (0-60 kg K ha-1) demonstrating significant yield gains, nodulation, nutrient uptake, and protein content enhancement in calcareous soils. It... Read more