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SoilDoc is a soil testing kit designed to determine site‐specific fertility status and enhance the accessibility of soil test services for smallholder farmers in the tropics. This study aimed to validate the use of the kit in the Southern Highlands (Mbeya and Njombe) and the Eastern Zone (Mvomero) of Tanzania. Composite soil samples collected from 144 smallholder farm fields were analyzed using 0.01 M CaCl2 extraction solution as per SoilDoc protocols. Out of 144 sites, 24 sites were randomly selected for nutrient response trials. The treatments were (i) absolute control, (ii) N alone, (iii) P Low N (Recommended P and half of recommended N), (iv) recommended NP, (v) NPK, (vi) NPS, (vii) NKS, and (viii) NPKS, replicated three times. Maize yields were subjected to analysis of variance. Relative yield for each nutrient applied was subjected to Cate and Nelson procedure to determine critical ranges. Across all sites, the control yielded least (0.55–5.20 Mg ha−1). Application of NPS, NPK, NP, or NPKS produced the highest yield (2.5–6.9 Mg ha−1). The SoilDoc critical ranges were 0.30–0.48 mg P kg−1; 0.15–0.27 cmolc K kg−1, and 4.1–4.8 mg S kg−1. Mbeya and Njombe soils appeared deficient in either NS, NP, NPK, or NPK, while in Mvomero 53% of soils were deficient in N alone and 31% of soils were deficient in NS. In the absence of field‐specific soil tests, applying N, P, S, and K in Mbeya and Njombe and N and S in Mvomero would be best bets for maximizing yield and return on fertilizer investment. Core Ideas: Maize (Zea mays L.) response to applied N, P, K, and S varied with SoilDoc test results.Application of NPS and NPKS resulted in highest maize yield of 2.5–8.8 Mg ha−1.The SoilDoc critical values are 0.30–0.48 mg P kg−1; 0.15–0.27 cmolc K kg−1, and 4.0–4.8 mg S kg−1.Nutrient‐deficiency groups consist of N alone, S alone, NS, NK, NP, NPK, NPS, NKS, and NPKS. [ABSTRACT FROM AUTHOR]

Securing a consistent food supply remains a pressing global challenge, particularly for small-scale farmers grappling with obstacles in enhancing agricultural yields, especially in tropical soils. Integrated Nutrient Management (INM) techniques, employing organic manures like vermicompost and bioenriched rock phosphate, emerge as recommended solutions. Vermicompost is lauded for its nutrient richness and positive soil health impacts. At the same time, bio-enriched rock phosphate serves as a sustainable alternative to conventional phosphorus fertilisers, specifically tailored for tropical soil conditions. Despite individual studies assessing the effects of vermicompost, bio-enriched rock phosphate, and soluble fertilisers on plant growth, a comprehensive overview of their combined application is noticeably lacking. To fill this gap, this study employs the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) method to explore the synergies of combining these elements and their impacts on crop production and the environment. This review is among the first to comprehensively summarize the complexities of combining vermicompost, bio-enriched rock phosphate, and chemical fertilisers on various crops. It thoroughly examines potential advantages, disadvantages, effects on agricultural systems, socio-economic implications, and existing policies governing their usage. Our findings reveal that the combined application of vermicompost, bio-enriched rock phosphate, and soluble fertilisers leads to significant improvements in plant growth, yield, and soil properties. The optimal impact is observed when vermicompost constitutes 25% and soluble fertiliser comprises 75 or 100% of the recommended fertiliser dosage. Moreover, incorporating a mixture of phosphate-solubilizing bacteria (PSB) strains in rock phosphate further enhances its positive effects. Despite these positive findings, we identified gaps in comprehensive approaches addressing socio-cultural dimensions and the lack of literature on prevailing policies regarding vermicompost use in agricultural systems highlighting the need for a more holistic understanding of vermicompost incorporation and a better grasp of the institutional frameworks guiding these practices. However, to secure sustainable crop production, farmers need to integrate vermicompost and biofertilisers with chemical fertilisers. In fostering the adoption of sustainable and inclusive agricultural practices on small rural properties, it is advisable to incorporate agricultural education into farmer training programs. [ABSTRACT FROM AUTHOR]

Nitrogen (N), phosphorus (P) and potassium (K) fertiliser application, was able to counteract growth reductions, in cassava cultivated on nutrient poor soils, under one water stress condition. It however remains to be seen, whether N, P and K fertiliser application, would produce similar results, across different water stress conditions. A study was therefore conducted to determine how N, P and K fertiliser application, would influence cassava growth on nutrient poor soils, under various water stress conditions. Effects on new leaf formation and leaf size were also investigated. The study was a 2×3×4 factorial pot experiment, in a randomised complete block design. It included: two cassava varieties, three water stress levels and four fertiliser treatments. The water stress levels kept some plants watered at field capacities of 30% (severe water stress), 60% (mild water stress) and 100% (zero water stress). The fertiliser treatments consisted of a control (no fertiliser), a sole K fertiliser treatment (25 mg K/kg), a moderate N, P and K fertiliser treatment (25 mg N + 5 mg P + 25 mg K/kg) and a high N, P and K fertiliser treatment (50 mg N + 13 mg P + 50 mg K/kg). All data were analysed using the analysis of variance. Cassava growth was assessed by monitoring changes in the dry shoot mass of cassava plants. High and moderate N, P and K fertiliser application, produced cassava plants with higher and similar dry shoot masses, under mild water stress (10.5 g/plant, SE = 0.6 and 9.0 g/plant, SE = 0.6, respectively). High N, P and K fertiliser application, however gave cassava the highest dry shoot mass, under severe water stress (7.9 g/plant, SE = 0.4). Relatively high cassava growth was consistently achieved with high N, P and K fertiliser application, across all water stress conditions., Competing Interests: The authors declare no conflict of interest., (© 2021 The Author(s).)

Soil moisture management and fertilizer micro-dosing on yield and land utilization efficiency of inter-cropping maize-pigeon-pea in sub humid Tanzania [1]. Farmers typically grow pigeon-pea as a mixed cropping system, the advances of these systems have been well studied, for example: increased productivity and rainfall infiltration. Much research has been done on cereal-pigeon pea intercropping on research stations, comparing yields in intercrops with sole maize. However, the role of inorganic fertilizers in sustainably intensifying intercropping systems has not been optimalised in all cases. For example in a recent study "Sustainable Intensification with Cereal-Legume Intercropping in Eastern and Southern Africa" published in Sustainability 2019, 11, 2891; https://doi.org/10.3390/su11102891, also the effect of inorganic fertilizers were studied. But usually these studies did not pay attention on the relation with water supply. Data in this article presents rainfall variability in the season and between seasons, yield of maize ( Zea mays cv. TMV1) and pigeon-pea ( Cajanus cajan cv. Babati White) under sole crop and intercropping. Yield of maize and pigeon-pea is analyzed under inter-row rainwater harvesting practices and fertilizer application in the field. Sole cropping and intercropping biological and/or economic yield are used to determine land use efficiency through land equivalent ratio. Comparisons between sites and seasons are done using a T-test., (© 2019 Published by Elsevier Inc.)