Tag: resources management
To control or not to control: how do we learn more about how agronomic innovations perform on farms?
Our paper ‘Loading the dice in favour of the farmer: reducing the risk of adopting agronomic innovations’ revealed mean increases but also large variation in the impact of four agroforestry practises on maize yield, as experienced by farmers in Malawi. This prompted a response from Sileshi and Akinnifesi that was critical of the data and methods used. Their main concern was that farmers did not necessarily manage crops identically in plots with and those without trees, so the yield differences that we measured may be partly caused by these differences in crop management. We argue here that it is valid and useful to look at the actual effect on crop yield of farmers having trees intercropped with maize, rather than controlling for how the crop is managed, because this is what happens in the real world. Farmers respond to having trees in their field by treating their crop differently, so this is part of the system response to having trees in fields. Attempts to eliminate this will result in measuring an artefact rather than the real impact of trees on crop yield. By doing this, we revealed important variation in the impact of trees on crop yield amongst farmers, and we argue that it is important to explore, assess and communicate to farmers and development actors the extent and implications of this variation. Understanding the contextual factors that determine who is likely to benefit most from an innovation and for whom it is less suitable can then be incorporated in scaling up, so that targeting of innovations and the appropriateness of messages given to farmers are continuously refined.
Nitrogen turnover and N2O/N2 ratio of three contrasting tropical soils amended with biochar
Biochar has been reported to reduce emission of nitrous oxide (N2O) from soils, but the mechanisms responsible remain fragmentary. For example, it is unclear how biochar effects on N2O emissions are mediated through biochar effects on soil gross N turnover rates. Hence, we conducted an incubation study with three contrasting agricultural soils from Kenya (an Acrisol cultivated for 10-years (Acrisol10); an Acrisol cultivated for over 100-years (Acrisol100); a Ferralsol cultivated for over 100 years (Ferralsol)). The soils were amended with biochar at either 2% or 4% w/w. The 15N pool dilution technique was used to quantify gross N mineralization and nitrification and microbial consumption of extractable N over a 20-day incubation period at 25 °C and 70% water holding capacity of the soil, accompanied by N2O emissions measurements. Direct measurements of N2 emissions were conducted using the helium gas flow soil core method. N2O emissions varied across soils with higher emissions in Acrisols than in Ferralsols. Addition of 2% biochar reduced N2O emissions in all soils by 53 to 78% with no significant further reduction induced by addition at 4%. Biochar effects on soil nitrate concentrations were highly variable across soils, ranging from a reduction, no effect and an increase. Biochar addition stimulated gross N mineralization in Acrisol-10 and Acrisol-100 soils at both addition rates with no effect observed for the Ferralsol. In contrast, gross nitrification was stimulated in only one soil but only at a 4% application rate. Also, biochar effects on increased NH4+ immobilization and NO3−consumption strongly varied across the three investigated soils. The variable and bidirectional biochar effects on gross N turnover in conjunction with the unambiguous and consistent reduction of N2O emissions suggested that the inhibiting effect of biochar on soil N2O emission seemed to be decoupled from gross microbial N turnover processes. With biochar application, N2 emissions were about an order of magnitude higher for Acrisol-10 soils compared to Acrisol-100 and Ferralsol-100 soils. Our N2O and N2 flux data thus support an explanation of direct promotion of gross N2O reduction by biochar rather than effects on soil extractable N dynamics. Effects of biochar on soil extractable N and gross N turnover, however, might be highly variable across different soils as found here for three typical agricultural soils of Kenya.
African nut – family Euphorbiaceae: Njansang, Okhuen, Bofeko, Musodo
Fast-growing tree, reaching upto 50m in height and 2.7 m i girth; Branches often short, thick and contorted ,3-5 leafe foliates alternate digitately; flowers form an infllorescence yellow tomentos; fruits are 2-3 lobed,2 celled and indehiscent with a thick cell hard shell. The smell of overripe apples;contain 2-3red-brown-black.seeds, are rounded and flat. seeds vary fromreddish brown to black and usually consist of a testa with a yellow kernel.
Potential for integrated landscape approaches: A review of Ghana’s national environment and development policies
Key messages
- <li.This brief explores Ghana’s national environment and development policy climate and whether it is conducive to operationalizing an integrated landscape approach (ILA).
- Ghana’s policy framework is geared towards large-scale, near-term development, raising questions regarding environmental impacts and related socioeconomic reverberations. Concerns surrounding future development plans stem from Ghana’s past and present challenges with competing land uses.
- Ghana has many policies and management schemes that support reconciling conservation and development needs; however, barriers to implementation persist.
- Challenge areas include: establishing a transparent change logic that is understood and endorsed across sectors and stakeholder groups. This requires identifying common concern entry points and clarifying rights and responsibilities.
- We suggest a greater commitment to these principles and the adoption of a landscape approach hold potential to enhance social and ecological outcomes in Ghana. Engaging with Ghana’s existing Community Resource Management Area (CREMA) program is an opportunity in this regard.