Can organic agriculture contribute to sustainable development in the tropics?

Agricultural intensification over last decades has resulted in a great increase of crop yields, but it also had a detrimental impact on biodiversity. The dramatic decline of arable weed diversity is a matter of great concern because weeds have an important ecological function as a key component of the food web of agroecosystems. Weeds are suitable indicators of management effects on wildlife diversity in arable crops because they have high sensitivity to cultivation measures and have a strong relation to other organism groups. Nevertheless, the effect of farming management on weed abundance and diversity will be more reliable on weed seed bank rather than on aboveground weed community because it is the result of processes that have occurred in the past and consequently, it could better reflect the effect of the agricultural practices over the years

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

Termite-induced injuries to maize and baby corn under organic and conventional farming systems in the Central Highlands of Kenya

Open Access Journal; Published online: 22 Oct 2019Termite-induced injuries to maize and baby corn were evaluated in on-going comparison experiments on organic and conventional farming systems at two trial sites in the Central Highlands of Kenya (Chuka and Thika). The farming systems were established in 2007 at two input levels: Low input level, representing subsistence farming (Conv-Low, Org-Low) and high input level, representing commercial farming (Conv-High, Org-High). Termite-induced injuries to maize and baby corn, such as tunneling the stem or lodging the whole plant were assessed over two cropping seasons. The lodging occurred exclusively at Thika. It first became apparent in the Org-Low system, with most of lodging occurring during the vegetative stage. Baby corn grown under high input systems showed increasing lodging from the late vegetative crop stage and peaked before the final harvest. Tunneling was recorded at both sites, but was generally below 5%, with no significant differences between the farming systems. Overall, the injury patterns caused by termites appear to be a function of the plant growth stage, termite colony activities, trial site, and the types and levels of fertilizer input. Thus, the management practice used in each farming system (organic or conventional) might have greater influence on crop injuries than the type of farming system itself or the termite abundance within each system

Karli

International audienc

Ellora

International audienc

Effect of 100% organic feeding on performance, carcass composition and fat quality of fattening pigs

In organic pig production, the aim is to achieve 100% organic feeding. According to the EU organic regulation (EC) No 889/2008 and the implementing regulation (EU) 2021/181, 100% organic feeding is mandatory for monogastric animals from 2022 onwards. This generates the challenge of achieving adequate protein quality in pig feed, which is currently still achieved by using 5% conventional components mostly in the form of potato protein. To investigate the effects of 100% organic feeding on growth performance, meat and fat quality in pigs, a total of 700 fattening pigs were studied in an on-farm feeding trial on three farms (A, B, C). The 95% organic diet fed on each farm was served as control diet (CON) and a 100% organic diet with higher soybean press cake and legume content was used as experimental diet (ORG). CON fed animals achieved with 867 g higher average daily weight gains than ORGfed animals with 825 g. Carcass weight and meat area were also reduced under diet ORG. A change in fatty acid composition in back fat was induced by diet ORG. Thus, iodine value (71.7 vs 73.7) and PUFA content (17.2 vs 19.2%) were significantly higher under this diet. 100% organic feeding seems to be associated with reduced performance and altered meat and fat quality. An adjustment of the requirements for performance, meat and fat quality of organic pigs at markets should therefore accompany the introduction of 100% organic feeding

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

Nitrogen leaching losses and balances in conventional and organic farming systems in Kenya

Organic farming has been proposed as a solution to foster agricultural sustainability and mitigate the negative environmental impacts of conventional farming. This study assessed N losses and soil surface N balances in conventional and organic farming systems in a sub-humid and semi-humid (Chuka and Thika) sites in Kenya. Nitrate–N (NO3−–N) leached was trapped at 1 m depth using the Self Integrating Accumulator core method and the changes in mineral-N were assessed at different soil depths and different crop growth stages. Both conventional and organic farming systems lost substantial amounts of NO3−–N at the early growth stages of all the crops. Cumulative NO3−–N leached was similar in all the farming systems in each cropping season. More NO3−–N was leached during potato cropping (22–38 kg N ha−1) than during maize (0.9–5.7 kg N ha−1) and vegetable cropping (1.9–2.9 kg N ha−1). Under maize cultivation, three times more NO3−–N was leached at Chuka site than at Thika site. During the potato cropping, between 79 and 83% of the N applied in the low input systems was leached, compared to 10–20% in the high input systems. Only Org-High exhibited a positive soil surface N balance (797–1263 kg ha−1) over a whole rotation period at both sites. We recommend reducing N applications for potato in all farming systems and at the early growth stages for all the crops in order to reduce N loss to the environment. We also recommend increasing N application rates in the low input systems and to developing a model to guide application of organic inputs