This study investigates the temporal dynamics of soil nutrient stocks, specifically nitrogen (N), phosphorus (P) and potassium (K), on Majorca Island (Spain). The present study analysed the impact of agricultural practices, land-use transformations, and climate fluctuations on soil nutrient profiles (0-25 cm) over 11 years (2006–2017) in agricultural soils. 108 soil samples were collected on the island in 2017 and compared with the previous sampling done in 2006. The same laboratory analyses methodology was used on both samplings (Kjeldahl method to evaluate soil N, Olsen method to calculate available P and exchangeable K content employing ammonium acetate). The results indicated a significant increase of approximately 10% in N levels, which highlights the critical role of organic matter accumulation and targeted management strategies in enhancing soil fertility. In contrast, P levels dropped, which can be attributed to enhanced soil erosion due to frequent flooding events and inefficient P fertiliser application in agricultural settings. K levels remained relatively stable, with slight variations influenced by soil texture and specific management practices. This research underscores the complex interplay among human activity, land use, and environmental factors in shaping soil nutrient composition. It further elucidates the weak spatial dependence observed in the soil nutrients of Majorca, influenced by crop variability, different agricultural treatments, and human intervention. Nutrient stock predictions were tailored to the land-use categories following traditional statistical approaches. Finally, the study calls for the adoption of sustainable agricultural methods to mitigate adverse effects on soil nutrient reserves and to enhance soil ecosystem health. With an in-depth analysis of temporal shifts and spatial variability, this research provides crucial insights into soil nutrient stock dynamics by offering guidance for strategic land management and conservation in Mediterranean agricultural environments.
Tag: conservation agriculture
How climate-smart is conservation agriculture (CA)? – its potential to deliver on adaptation, mitigation and productivity on smallholder farms in southern Africa
Climate resilient cropping systems are required to adapt to the increasing threats of climate change projected for Southern Africa and to better manage current climate variability. Conservation agriculture (CA) has been proposed among technologies that are climate-smart. For a cropping system to be labelled “climate-smart” it has to deliver three benefits: a) adapt to the effects of climate and be of increased resilience; b) mitigate climate effects by sequestering carbon (C) and reducing greenhouse gas emissions (GHG); and c) sustainably increase productivity and income. Research on smallholder farms from Southern Africa was analysed to assess if CA can deliver on the three principles of climate-smart agriculture. Results from Southern Africa showed that CA systems have a positive effect on adaptation and productivity, but its mitigation potential lags far behind expectations. CA systems maintain higher infiltration rates and conserve soil moisture, which helps to overcome seasonal dry-spells. Increased productivity and profitability were recorded although a lag period of 2–5 cropping seasons is common until yield benefits become significant. Immediate economic benefits such as reduced labour requirements in some systems will make CA more attractive in the short term to farmers who cannot afford to wait for several seasons until yield benefits accrue. The available data summarizing the effects of CA on soil organic C (SOC) and reductions in greenhouse gases, are often contradictory and depend a great deal on the agro-ecological environment and the available biomass for surface residue retention. There is an urgent need for more research to better quantify the mitigation effects, as the current data are scanty. Possible co-interventions such as improved intercropping/relay cropping systems, agroforestry and other tree-based systems may improve delivery of mitigation benefits and need further exploration.
Looking back to look ahead: insight into the effectiveness and efficiency of selected advisory approaches in the dissemination of agricultural technologies indicative of Conservation Agriculture with Trees in Machakos County, Kenya
Sub-Saharan Africa is facing a challenge of low agricultural productivity, which threatens the ability to achieve food security for the continent’s growing population. The low productivity has been attributed to a number of factors including climate variability and low soil fertility. Agricultural practices such as Evergreen Agriculture show promise in improving soil fertility and production in a sustainable way. One form of Evergreen Agriculture is Conservation Agriculture with Trees (CAWT), which combines the principles of Conservation Agriculture with tree-crop intercropping. The promotion of complex agricultural practices such as CAWT requires agricultural advisory approaches that are both effective and efficient. Effective in their ability to increase diversity of crop enterprises, productivity of staple crops and adoption of promoted relevant practices. Advisory approaches are also considered effective if they provide useful information and build social networks in the community. The approaches also need to be efficient, that is, be able to mobilize the community and provide training in a costand- time appropriate fashion.
The political economy of Readiness for REDD+
Conservation agriculture (CA) is promoted extensively to increase the productivity and environmental sustainability of maize production systems across sub-Saharan Africa and is often listed as a climate-smart agriculture (CSA) practice. However, the impacts of CA on food security, resilience/adaptive capacity and climate change mitigation are location-dependent and it is unknown whether CA can simultaneously address CSA’s multiple objectives. Here we evaluate four variations of CA: reduced tillage plus mulch (mulch), reduced tillage plus mulch and leguminous cover crop (Lablab), reduced tillage plus mulch and leguminous trees (CAWT), and reduced tillage plus mulch and nitrogen fertilizer (CA + F)-for their effect on CSA-relevant outcomes in highland Tanzania maize production. By comparison to conventional practice in the region, intensification of maize production by Lablab, CAWT, and CA + F significantly increases yields by 40, 89 and 77 %, respectively. Likewise, rainfall use efficiency was highest in these three treatments and significantly greater than conventional practices in 7 of 12 comparisons. Seasonal and annual greenhouse gas fluxes were similar across all treatments; however, yield-scaled global warming potential (Mg CO2 eq Mg grain-1) was lower in CAWT (2.1-3.1) and CA + F (1.9-2.3) than conventional practice (1.9-8.3), averaging 62 and 68 % of the emission intensity of conventional practice, respectively. The findings demonstrate that CA can deliver benefits consistent with the objectives of CSA for farmers in this region, particularly when soil nitrogen limitation is alleviated, providing other constraints to adoption are removed.