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Rainwater harvesting from Roads For Indigenous Pasture production and improved rural livelihoods in Kitui, Kenya (ROFIP) is an applied research project. It assessed the potential of combining multiple sustainable land management practices, for example native grass reseeding, rainwater harvesting from roads and in situ microcatchments to enhance vegetation cover in a semi-arid dryland in Kenya. Rural earth roads were used as a catchment. Runoff generated from rainfall events was diverted into reseeded pastures with trenches established at intervals, across a slope. The ROFIP project also integrated microcatchments created using ox-driven ploughs, a traditional practice for seedbed preparation and harnessing in situ rainwater harvesting in African drylands. Combining the diversion of runoff from roads and harvesting rainwater in situ improves and prolongs soil moisture availability in reseeded pastures. Consequently, this translated to higher biomass yields (i.e. forage for livestock) and vegetation cover (land degradation mitigation and enhanced soil health). This project clearly showed that combining rainwater harvesting and native pasture reseeding improves water retention and soil health, thus improving sustainable pasture production. However, for this to be achieved, it is prudent to involve practitioners to co-design practical solutions that are socially, economically and environmentally sustainable. Multi-stakeholder engagement, effective knowledge sharing, and community involvement can be major enablers in the pursuit of environmental and socioeconomic relevant benefits in applied research projects in Africa. This approach enhances a sense of shared purpose among practitioners and empowers them to become points of reference to their peers.

Addition of labile carbon (C) inputs to soil can accelerate or slow down the decomposition of soil organic matter (SOM), a phenomenon known as priming effect (PE). However, the magnitude and direction of PE is often difficult to predict, consequently making its relationship with labile C inputs and nutrient availability elusive. To assess this relationship, we added 13C labelled glucose (corresponding to 50% of initial soil microbial biomass C) to two soil types (Vertisol and Acrisol) with different concentrations of available N and from four land use systems (agricultural, pasture, grassland and shrubland). Parallel laboratory incubations i.e. short-term (6 days) and long-term (6 months), were set up to determine the effect of land use and soil type (N availability) on PE. Addition of labelled glucose in solution led to the retardation of SOM mineralization (negative PE) in both soil types and across all land use systems. This is attributed to preferential substrate utilization characterized by the higher mineralization of added glucose. Land use systems and soil types with higher N-availability displayed weaker negative PE, which is in line with the stoichiometric decomposition theory. In conclusion, our study demonstrate that N-availability plays a major role in determining mineralization of labile C inputs, magnitude and direction of PE in the studied dryland soils and land use systems. The fact that 15–27% of the added 13C remained in the soil at the end of the 6 months incubation and PE was negative, indicates that continuous labile C inputs could contribute to C immobilization and stabilization in these semiarid soils. Moreover, 13C glucose remaining in soils after 6 months in semi-natural pastures was comparable to those under natural grassland and shrubland systems especially in Acrisols. This demonstrates that incorporation and maintaining a perennial cover of native pastures has the potential to increase C sequestration in African semi-arid agricultural soils and landscapes.

Soil microbial carbon-use efficiency (CUE), described as the ratio of growth over total carbon (C) uptake, i.e. the sum of growth and respiration, is a key variable in all soil organic matter (SOM) models and critical to ecosystem C cycling. However, there is still a lack of consensus on microbial CUE when estimated using different methods. Furthermore, the significance of many fundamental drivers of CUE remains largely unknown and inconclusive, especially for tropical ecosystems. For these reasons, we determined CUE and microbial indicators of soil nutrient availability in seven tropical forest soils along an altitudinal gradient (circa 900–2200 m a.s.l) occurring at Taita Hills, Kenya. We used this gradient to study the soil nutrient (N and P) availability and its relation to microbial CUE estimates. For assessing the soil nutrient availability, we determined both the soil bulk stoichiometric nutrient ratios (soil C:N, C:P and N:P), as well as SOM degradation related enzyme activities. We estimated soil microbial CUE using two methods: substrate independent 18O-water tracing and 13C-glucose tracing method. Based on these two approaches, we estimated the microbial uptake efficiency of added glucose versus native SOM, with the latter defined by 18O-water tracing method. Based on the bulk soil C:N stoichiometry, the studied soils did not reveal N limitation. However, soil bulk P limitation increased slightly with elevation. Additionally, based on extracellular enzyme activities, the SOM nutrient availability decreased with elevation. The 13C-CUE did not change with altitude indicating that glucose was efficiently taken up and used by the microbes. On the other hand, 18O-CUE, which reflects the growth efficiency of microbes growing on native SOM, clearly declined with increasing altitude and was associated with SOM nutrient availability indicators. Based on our results, microbes at higher elevations invested more energy to scavenge for nutrients and energy from complex SOM whereas at lower elevations the soil nutrients may have been more readily available.

Agricultural ecosystems are facing critical loss of biodiversity, soil nutrients, and cultural values. Intensive crop production has caused landscape homogenisation, with trees and hedges increasingly disappearing from agricultural land. Changes in farming practices are essential to increase biodiversity and improve soil biogeochemical processes, such as nutrient cycling, soil carbon uptake, and sequestration, as well as to improve the resilience and fertility of farming systems. Agroforestry is an important practice for implementing and improving natural and cultural value of landscapes, but in northern countries, agroforestry methods remain rarely utilised. Our study was conducted in Southern Finland on an agricultural field where a row of willow and alder was planted 6 years prior to our study. We concentrated on the effects of the tree row on crop growing conditions and how far from the trees possible impacts can be observed. We studied soil properties, carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) exchange, and soil microbial communities. The impact of trees on crop growing conditions, biomass production, and greenhouse gas fluxes was modest and did not extend further than few meters from the tree row in the warm and dry growing season of 2019. N2O and CH4 fluxes were negligible and the tree row did not increase greenhouse gas emissions from soil. Soil microbial diversity was clearly improved by the presence of trees due to more diverse habitats. The tree row also slightly decreased the estimated annual net emissions of carbon into the atmosphere. Due to positive indications of the effects of agroforestry on biodiversity and carbon uptake, we highly recommend further studies within various agroforestry practices in Nordic countries.

Land degradation is a major problem in the semi-arid environments of Sub-Saharan Africa. Fighting land degradation is essential to ensure the sustainable and long-term productivity of the inhabited semi-arid lands. Cenchrus ciliaris (African foxtail grass), Enteropogon macrostachyus (bush rye) and Eragrostis superba (Maasai love grass) are important perennial grasses in the Eastern African semi-arid lands. A study was conducted to establish the contribution of these indigenous grasses in improving soil hydrological properties, rehabilitation, food security and the livelihoods of agro-pastoral communities in semi-arid districts of Kenya. Soil hydrological properties were tested using a Kamphorst simulator at different stubble heights to represent three different grazing intensities (low, medium, high). Ground cover was estimated using the step-point method. A survey was also conducted across 50 agro-pastoral households to establish the multidimensional benefits of the grasses. Sediment production (as a function of run-off and infiltration capacity) was significantly different (P

La dégradation du sol constitue un problème majeur dans les zones semi-arides d'Afrique subsaharienne. La lutte contre cette dégradation du sol est capitale pour garantir une productivité durable et à long terme des terres semi-arides habitées. Le Cenchrus ciliaris (vulpin des prés africains), l'Enteropogon macrostachyus (seigle sauvage) et l'Eragrostis superba (Eragrostis Maasai) sont d'importantes graminées vivaces dans les zones semi-arides d'Afrique de l'Est. Une étude a été faite pour évaluer la contribution de ces herbages graminacées indigènes à l'amélioration des propriétés hydrologiques du sol, la réhabilitation, la sécurité alimentaire et les moyens de subsistance des communautés agro-pastorales dans les districts semi-arides du Kenya. Les propriétés hydrologiques du sol ont été testées à l'aide d'un simulateur Kamphorst, à diverses hauteurs de chaume, pour donner une image de trois différentes intensités de pâturage (faible, moyenne, élevée). L'estimation de la couverture végétale s'est faite à l'aide de la méthode d'échantillonnage step-point. Une étude a également été réalisée dans 50 ménages agro-pastoraux pour évaluer les avantages multidimensionnels des herbages graminacées. La production de sédiments (comme fonction d'écoulement et capacité d'infiltration) était considérablement différente (P

Enteropogon macrostachyus (Bush rye), Cenchrus ciliaris L. (African foxtail grass) and Eragrostis superba Peyr (Maasai love grass) are important perennial rangeland grasses in Kenya. They provide an important source of forage for domestic livestock and wild ungulates. These grasses have been used extensively to rehabilitate denuded patches in semi-arid environment of Kenya. This study investigated the dry matter yields and hydrological properties of the three grasses under simulated rainfall at three phenological stages; early growth, elongation and reproduction. Laboratory seed viability tests were also done. Hydrological properties of the three grasses were estimated using a Kamphorst rainfall simulator. Results showed that there was a significant difference (p > 0.05) in dry matter yields and soil hydrological properties at the different grass phenological stages. Generally, all the three grasses improved the soil hydrological properties with an increase in grass stubble height. C. ciliaris gave the best soil hydrological properties followed by E. macrostachyus and E. superba, respectively. E. macrostachyus recorded the highest seed viability percentage. C. ciliaris and E. superba were ranked second and third, respectively. C. ciliaris yielded the highest biomass production at the reproductive stage followed by E. superba and E. macrostachyus, respectively.