No abstract

Application of vermicompost in crop production results in improved soil chemical properties. Studies relating to use of vermicompost as alternative to synthetic fertilizers have gotten considerable attention as the demand for organically produced agricultural products increases. Goat manure has been reported to be rich in nitrogen, phosphorous and potassium. However, preparation and utilization of goat manure-based vermicompost in organic garlic production in the study area is scanty. Thus, farmers have solely relied on chemical fertilizers in garlic production which is a health and environmental hazards and causes ground and surface water pollution due to nitrate leaching. In Manyatta sub-county of Eastern Kenya, farmers use synthetic fertilizers in garlic production which is not sustainable despite having readily available goat manure which can be composted for use. The aim of this study was to prepare and evaluate effectiveness of goat manure-based vermicompost for organic garlic production in Manyatta sub-county, Kenya. Goat manure-based vermicompost was prepared at KALRO Embu station, Embu County between July-November 2018. The vermicompost obtained was dried, screened and filled into bags and was used for growing garlic. A sample of goat manure-based vermicompost was analysed for chemical properties and the results showed that it had very high total N (1.79%), very high available P (52 ppm), very high exchangeable K (1.75 Cmol Kg -1 ) and it was moderately alkaline (pH 7.73). Hence, goat manure-based vermicompost is recommended in the organic production of garlic in Manyatta sub-county of Eastern Kenya.

Soybean (Glycine max) is an important legume crop that is cultivated all over the world as livestock feed, food for human consumption, soil fertility improvement and industrial products such as candles and paints. However, Nitrogen (N) and phosphorus (P) nutrient have been attributed to the decline in soybean yields. Furthermore, scanty information is documented on P-efficient soybean genotypes, which are a sustainable P management strategy for enhancing symbiotic efficiency (SEF) and phosphorus use efficiency (PUE). As a solution, field experiment was conducted at Chuka University farm to evaluate the integration effect of rhizobium inoculation (R) and P on tissue nutrient content, SEF and PUE in soybean production in Meru South Sub County. Two cultivations (Trial I and II) were done in 2018. Treatments included; three rates of R (0, 100 and 200 g ha -1 ), three rates of P (0, 20 and 30 kgha -1 ), either applied alone or integrated and soybean genotypes (SB19 and SB24). Both Trials were laid out in a randomized complete block design in split-split plot arrangement with each treatment replicated thrice. Genotypes were assigned main plot, R subplots and P in sub-subplots. Data collected was subjected to analysis of variance using the Scientific Analysis System SAS and significantly different means separated using Tukey test at (p≤0.05). The results showed significant difference in N and P tissue content, SEF and PUE for SB19 and SB24 genotypes in both Trials at (p≤0.05). The highest N tissue content of between 1.73% and 9.10% was observed when integration of R and P were applied at the rate of 200 g and 30 kg for SB19 and SB24 in both Trials. While R and P at the rate of 200 g and 30 kg per ha showed the highest P content of between 849.6 ppm and 955.0 ppm in both Trials. The highest SEF recorded was 207% and 261%, and 201% and 227% in Trials I and II, respectively. The PUE was highest when R and P was applied at the rate of 200 g and 30 kg per ha for SB19 and SB24 soybean in both Trials. Integration of R and P at the rate of 200 g and 30 kg ha -1 and adoption of either SB19 or SB24 showed a potential in enhancing soybean cultivation.

Green gram is an important drought tolerant grain legume crop in Kenya. In Tharaka Nithi County green gram is as a major source of food security. Hence, there is need for a cheap and sustainable system of agricultural production is needed to increase its production. The legume/Rhizobium symbiosis in combination with phosphate rock offers a natural system for improving green gram nitrogen fixation. Therefore, this study was aimed at determining the effect of Rhizobium and phosphate rock fertilizer application on growth and yield attributes of N26 and KS20 varieties. The study was carried out at Chuka University Horticultural Research Farm for two seasons, November 2019 to January 2020 and February to April 2020. Factorial experiment of 2x2x2 was laid out in a Randomized Complete Block Design (RCBD). There were three factors, variety (N26 and KS20), phosphate rock (0 and 30 kg P ha-1) and Rhizobium MEA 716 (0 and 100 g ha-1). The experiment contained eight treatments which were replicated three times. The data was collected fortnightly on four randomly selected plants on parameters such as plant height, number of leaves, branches, pods, total dry biomass, shoot and root dry weight and grain yield. These data was analysed using Statistical Analysis Software (SAS). Significant means are separated using Least Significant Difference (LSD) at probability level of 5%. Results for both seasons indicated that combined application of Rhizobium MEA 716 Rhizobium 100 g ha-1 and phosphate rock 30 Kg ha-1 phosphate under variety  in treatment (R1P1V2) showed significantly (P<0.05) higher  plant height (76.07 cm), number of branches (14.08 plant-1), shoot dry biomass (52.01 g plant-1), root dry biomass (7.60 g plant-1), total dry biomass (146.4 g plant-1), number of pods (84 plant-1) and yield (2158 kg ha-1) compared to variety N26 in treatment (R1P1V1).  Therefore, combination of Rhizobium MEA 716 100 g ha-1 and phosphate rock 30 Kg ha-1 under variety KS20 led to improved growth attributes equally yield components of KS20 variety over N26. From these findings, application of Rhizobium MEA716  at 100 g ha-1, and 30 Kg ha -1  phosphate rock under variety KS20 was recommended for improved and a sustainable green gram production in  the study area.

Soil fertility decline is one of the major constraints in agricultural productivity. Biological nitrogen fixation (BNF) in legumes can offer a cost-effective and sustainable means towards soil fertility management. There is limited information on green-gram BNF enhancement through Rhizobium inoculation with rock phosphate fertilizer. The objective of this study was to determine the effects of Rhizobium and rock phosphate fertilizer application on soil chemical properties under green-gram varieties. The study was carried out at Chuka university horticultural research farm in two seasons (November 2019 - January 2020 and February - April 2020). A factorial experiment of 2 x 2 x 2 was laid out in a randomized complete block design (RCBD). There were three factors; varieties (N26 and KS20), rock phosphate (0 and 30 kg P ha-1) and Rhizobium inoculation (0 and 100 g ha-1) making a total of eight treatments which were replicated three times. Soil sampling and analyses were done for soil pH, fixed-N, total nitrogen (TN), exchangeable cations (EC), available Phosphorous (P), total organic carbon (TOC), and exchangeable potassium (K) before planting and after harvesting of green-grams for the two seasons. Data was analysed using GENSTAT 15th edition (P≤0.05). Results from both seasons indicated that combined application of rock phosphate at 30 kg P ha-1 and Rhizobium inoculation at 100 kg ha-1 showed significant (P≤0.05) higher increase in soil chemical properties over other treatments. However, treatment R1P1KS20 recorded significantly higher results in soil pH (7.54), TN (0.58%), TOC (3.45%), P (68.20 ppm) and EC (0.95 CmolKg-1), fixed-N (0.50%) and K (1.75 CmolKg-1). On the other hand treatment R0P0N26 recorded significant (P≤0.05) lower results in soil pH (5.23), TN (0.04%), TOC (1.86%), P (8.76 ppm), EC (0.21 CmolKg-1) and K (0.58 CmolKg-1). Therefore, Rhizobium inoculation in green-grams in combination with rock phosphate is an important legume nitrogen fixation enhancement method. This method is cost effective for farmers in sustainably supplementing nitrogen and phosphorous in their farms for improved soil fertility management. Based on the findings, combining Rhizobium 100g ha-1 and rock phosphate 30 kg P ha-1 with variety KS20 were recommended for a sustainable soil fertility management in Tharaka Nithi County.