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There is a growing demand for organic vegetable products. Increasing the marketable yield and quality of tomatoes through the use of optimal organic and inorganic fertilizers is a critical agronomic measure for crop productivity and soil health. However, little is known about the effects of Azolla on tomato productivity, fruit quality and soil organic changes. The aim of this study was to compare the effects of organic and inorganic fertilization on marketable yield and quality characteristics of tomato fruits. A pot experiment was conducted with four concentrations of Azolla and nitrogen in a completely randomized design. The results showed that Azolla has the potential to replace nitrogen and has a significant impact on fruit quality. The interactions of Azolla and nitrogen on the number of clusters per plant, the number of flowers per cluster, the proportion of fruit set, the number of fruits per cluster and the marketable fruit yield were significant. It can be concluded that the combination of Azolla and inorganic nitrogen fertilizer linearly increased the marketable yield and quality of tomato fruits. [ABSTRACT FROM AUTHOR]

Increasing maize production is vital for contributing to smallholder farmers' food security since it ranks second in production after wheat. However, the decline in soil fertility is a marked constraint to crop productivity in developing countries, particularly in maize production. Recently, organic amendments through liquid bio-slurry enhanced maize productivity and improved food security via changes in soil physico-chemical properties for smallholder farmers in developing countries like Ethiopia. However, the utilization of liquid bio-slurry as an organic amendment has not been extensively investigated in the study areas. Therefore, field experiments were conducted at two sites to determine the optimum combination of inorganic N and liquid bio-slurry for improving maize productivity. A factorial combination of two mineral N (0 and 46 kg ha-1) and five liquid bio-slurry (0, 6, 12, 18 and 24 t ha-1) rates were used in a randomized complete block design with three replications. The results revealed that the combined use of N and liquid bio-slurry improved the growth and yield of maize in the two experimental sites. Plant height, ear length, number of rows per ear, number of kernels per ear, above-ground dry biomass, hundred-grain weight, grain yield and straw yield of maize were all improved by applying 46 kg N ha-1 along with 18 t liquid bio-slurry ha-1. The highest grain yield (8.12 t ha-1) was achieved from the combined application of 46 kg N ha-1 with 18 t liquid bio-slurry ha-1. Thus, using 46 kg N ha-1 with 18 t liquid bio-slurry ha-1 is highly recommended to increase the yield of maize. [ABSTRACT FROM AUTHOR]

Phosphorus (P) transformations and associated changes in soil chemistry following lime application in acidic soils are very determinant to enhance P use efficiency. Thus, this study was conducted to evaluate the effects of different rates of lime on soil P fractions and chemical properties in acidic Luvisols of southern Ethiopia. The lime rates were 0 t/ha (0%), 3.75 t/ha (50%), 7.5 t/ha (100%), and 11.25 t/ha (150%), and incubated for a month with three replications. The soil P fractions analyzed includes soluble P (P-sol), P associated with iron (Fe-P), aluminum (Al-P), calcium (Ca-P), organic part (Org-P) and residual (Res-P). The result indicated that liming significantly (p < 0.05) improved the release of P-sol, Ca-P, and Res-P, and reduced Fe-P, Al-P, and Org-P. The changes in soil chemical properties were also significant. For instance, increased rate of lime enhanced soil pH from 5.3 to 6.5, reduced exchangeable acidity from 1.47 to 0.15 cmol(+)/kg, and increased available P from 2.74 to 8.72 cmol(+)/kg. Yet, the amount of P-sol was found low for plant needs even at a 150% rate of lime. Thus, working on external P requirement to equilibrate the need for plants followed by crop response validation are suggested. [ABSTRACT FROM AUTHOR]

This study investigated phosphorous (P) sorption characteristics under lime rates, and validated them under field conditions. Soil samples from nitisols and luvisols were taken, mixed with lime(tha−1) at[0,0], [5.25, 3.75], [10.5, 7.5] and [15.75, 11.25], respectively, and incubated for 30 days. It was equilibrated with KH2PO4 at 0, 10, 20, 30, 40, and 50 mgPL−1. The data were tested with Freundlich and Langmuir models. External P requirement (EPR) and changes in chemical properties were evaluated. The field validation on wheat involved rates of P (0, 8.2, 16.4, 24.6, 32.9, and 41.1 kg ha−1) and lime (0, 650, and 1300 kgha−1) in a randomized complete block design with three replications. Freundlich was found the best-fitted model. Freundlich coefficient (Kf) ranged from 212 to 45 mgPkg−1 (nitisols) whereas it was 112.7 to 16.29 mgPkg−1 (luvisols). EPR (kgPha−1) without and the highest lime rate were: nitisols (142.5 and 52.32 kgPha−1) and luvisols (124.84 and 25.94 kgPha−1). Liming reduced EPR by 63.3% (nitisols) and 79.3% (luvisols). Liming increased soil pH from [4.55 to 6.60 in the nitisols, and 5.33 to 6.51 in luvisols]; exchangeable acidity (cmol(+)kg−1) 3.84 to 0.01 nitisols, and 0.72–0.05 luvisols, and available P (mg/kg) 3.2–6.32 nitisol, and 2.74–8.72 luvisols. Furthermore, applying 32.9 kgPha−1 x 1300 kgha−1 lime resulted in grain yield (4345.2 kgha−1) that was 449% more than the untreated crop (791.3 kgha−1). The validation result suggested higher P than blanket P recommendation. It also justifies that excess P or lime alone cannot be a complete solution for P management and increased yield. [ABSTRACT FROM AUTHOR]

Although numerous factors contribute to wide yield gaps, low external inputs, particularly N, and poor cropping practices such as soil tillage and monocropping are among the major factors affecting low maize production. In view of this, field experiments were implemented on two sites with Cambisols and Chernozem soil types in two consecutive years to evaluate the impacts of different soil management practices on the grain yield and quality, nitrogen uptake, and selected soil properties. A three-factor experiment was arranged as a split-split plot arrangement randomized complete block design with three replications. The minimum tillage (MT) and conventional tillage (CT) were used as the main plot, haricot bean-maize rotation and maize monocropping were used as the subplot, and four levels of nitrogen fertilization (control, 20 t ha-1 compost, 46 kg N ha−1 + 10 t ha−1 compost, and 92 kg N ha−1) were used as the sub-subplot. Analysis of variance showed that soil management practices were significantly affecting grain yield, N-uptake, and soil properties. In sites, the conventional tillage and rotation system increased the grain yield and N-uptake in contrast to the minimum tillage and monocropping, respectively. Similarly, nitrogen evidently affected the grain yield, N-uptake, and selected soil properties. However, tillage methods differed in their effects on soil chemical properties; soil organic carbon and total nitrogen concentrations were improved through MT compared to CT. Grain yield was significantly associated with NDVI, grain N-content, and N-uptake. Therefore, a CT plus haricot bean-maize rotation system with the addition of solely 92 kg N ha−1 and integrated 46 kg N ha−1 + 10 t compost ha−1 could be recommended for Hawassa Zuria (Cambisols) and Meskan (Chernozem) districts, respectively. However, in order to ensure sustainable maize production in the investigated areas, an integrated N treatment with MT and a rotation system may be recommended, which could improve soil properties. [ABSTRACT FROM AUTHOR]