Organic maize and bean farming enhances free-living nematode dynamics in sub-Saharan Africa

Published online: 03 Jan 2022Despite their important ecological roles for soil health and soil fertility, free-living nematodes (FLN) have received relatively limited research attention. The present study evaluated the community structure and diversity of FLN in a field setting. The experiments were conducted in on-farm and on-station field plots sown to maize (Zea mays) and beans (Phaseolus vulgaris) under four cropping practices. These farming systems included organic (compost and biopesticide use), conventional (synthetic fertilizer and pesticide applications), farmer practice (organic and synthetic amendments) and a control (non-amended plots). Nineteen genera of free living nematodes, belonging to bacterivores, fungivores, omnivores and predators were recorded. Among these, bacterivores (Cephalobidae and Rhabditidae) were the most dominant group in the organic systems when compared to the conventional and control systems. Farming systems influenced the abundance and diversity of free living nematodes, with the organic farming system having higher values of maturity, enrichment and structural indices than other farming systems. This would indicate greater stability in soil health and improved soil fertility. This implies that the organic farming systems play a key role in improving the biodiversity and population buildup of FLN, compared with other systems. Our study helps to improve our understanding of how farming systems influence soil biodynamics, while studies on the longer-term effects of organic and conventional farming systems on the build-up or reduction of free living nematodes for improved ecosystem services are needed

Influence of pyrolyzed sludge use as an adsorbent in removal of selected trace metals from wastewater treatment

Abstract: Please refer to full text to view abstract

Managing phosphate rock to improve nutrient uptake, phosphorus use efficiency, and carrot yields

The objectives of this study were to assess (a) the efficiency of lemon and pineapple juices and the concentration and time needed to release more than 50% of available phosphorus from phosphate rock (PR), and (b) the effect of different types of PR management on carrot yields, nutrient uptake, and phosphorus use efficiency. Field trials were set up at two sites with humic andosols and orthic acrisols over two seasons in Kenya. In a randomized complete block design, replicated three times, the following treatments were compared: (i) composted dissolved PR in lemon juice; (ii) powdered PR composted; (iii) dissolved PR in lemon juice added to compost; (iv) powdered PR and compost; (v) triple superphosphate and compost; (vi) compost alone; (vii) triple superphosphate and Tithonia diversifolia mulch; with (viii) un-amended soil as a control. Lemon juice was effective in solubilizing PR, releasing 63% of the total phosphorus applied into available phosphorus, compared to 11% for pineapple juice and 6% for water. The combined application of compost and PR dissolved in lemon juice at planting significantly increased phosphorus and potassium uptake, phosphorus use efficiency, and carrot yields that was comparable to the use of triple superphosphate and compost. The study concludes that the dissolution of phosphate rock with lemon juice at a ratio of 1:5 phosphate rock to lemon juice and its combined application (immediately after dissolution) with compost at planting improves nutrient uptake, phosphorus use efficiency, and crop yields. We recommend further studies to explore the possibility of using citrus peels or other acidic organic materials to enhance the solubility of phosphate rock, and to assess their practical feasibility and the economic advantage(s) in the large-scale production of high value crops