Integrated water and soil conservation for food security in Niger, preliminary results

As a result of growing population pressure and limited fertile land availability, Nigerien farmers increasingly rely on marginal lands for food crops production. These degraded lands, however, generally provide poor millet yields due to their low soil nutrient content and imbalanced partitioning of water in the root-zone. This study evaluates the agronomical, hydrological and soil quality parameters of water and soil conservation techniques (i.e. zaï, demi-lunes and no-till with scarification) which tackle these two major crop growth limitations by means of an in situ root-zone water balance experiment. Preliminary results from the first cropping season from June to October 2011 show overall low yields. The 2011 season was characterised by erratic rainfall with a severe dry spell during flowering stage. The control and manure treatment did not yield grain, but simply applying manure did increase dry matter production with a factor of 20. The highest grain yield was produced by the zaï, 134 kg/ha, which was 3 and 9 times better than respectively the grain yield of demi-lunes and no-till with scarification treatments. The zaï treatment moreover reduced cumulative actual evaporation as measured using mini-lysimeters during a 10 day drying cycle. In conclusion, until now the synergistic effect of the water-harvesting practices and the supply of manure show promising potential to rehabilitate and to increase the agronomic efficiency of marginal land in Niger. Future work will focus on the impact of the treatments on yield, soil quality properties and on the root-zone water balance

Desertification and Degradation Risks vs Poverty: A Key Topic in Mediterranean Europe

Land degradation and, subsequently, desertification processes are conditioned by biophysical factors and human impacts. Nowadays, there is an increasing interest by social scientists to assess its implications. Especially, it is relevant to the potential changes and landscape deterioration on population, economic systems and feedbacks of local societies to such adjustments. Assessing social facets should also be related to desertification risks, integrated socio-economic inputs and environmentally sustainable development perspectives. However, investigations about the effects of land degradation conditioned by global socioeconomic-factors from a holistic point of view are scarce. In this review, we pretend to discuss past and recent findings on land degradation risks related to poverty, especially based on Mediterranean Europe. To achieve this goal, we focused on key socioeconomic forces such as developmental policy, production and market structure, social change and population mobility. Our review showed that regional disparities based on complex dynamics of demographic forces (e.g. migration, fertility and ageing) and economic drivers of change (e.g. industrial concentration, urbanization, crop intensification, tourism pressure, coastalization) are keys to understand Mediterranean regions such as Southern Italy, a region exposed to high desertification risk in Europe. We concluded that the overexploitation of territories, soil and water degradation urban expansion, tourism and unplanned industrialization are some sectors and activities which can be highly affected by political and socioeconomic forces leading to unsustainable forms of land management and types of development. Special attention should be paid to social policies, education and training schemes to reduce rural migration and potentiate territorial knowledge to avoid land degradation, considering other social issues such as poverty or centralization. The potential role of win-win policies abating poverty and reducing desertification risk is evident in Mediterranean Europe and achieving land degradation neutrality necessary

Integrated biophysical and socio-economic evaluation of water and soil conservation techniques : a case study from Niger

As a result of growing population pressure and limited fertile land availability, Nigerien farmers increasingly rely on marginal lands (Plinthosols) for crop production. These degraded lands, however, generally provide poor millet yields (<100 kg ha-1 yr-1) due to their low soil nutrient content and imbalanced partitioning of water over the root-zone. This dissertation aims to provide scientific verification of the potential of small-scale water and soil conservation (WSC) techniques to tackle these two major crop growth limitations. The overall objective is to evaluate the biophysicail and socio-economic viability of WSC techniques in the Tillaberí region of Niger. In order to monitor WSC techniques, a field experiment was laid on a Plinthosol nearby Sadoré. The treatments include: zaï + manure (Z), demi-lunes + manure (DL), scarification + manure (SCAR), control + manure (CF) and control (C). Grain yields for the conventional practices (C and CF) were extremely low and soil-water storage in the rootzone remained below the critical value for drought stress, even if there was sufficient rainfall. WSC techniques, on the other hand, successfully mitigated drought stress. WSC increased grain yields to 700 kg ha-1 yr-1 for Z and to 250 kg ha-1 yr-1 for DL and SCAR. By applying WSC, soil-water storage increased above the critical value for drought stress. This was mainly a result of significant run-off reduction under WSC (i.e. from approximately 25% for C to 5-10%). WSC techniques were, on the other hand, found to have only little impact on soil evaporation. A design optimization study with a three-dimensional coupled surface-subsurface soil hydrological model showed that rainwater use efficiency of DL could be improved by increasing the density of DL bunds per surface area while decreasing the number of millet plants per DL bund. Soil quality analysis showed that, SOC content increased significantly for the treatments with manure application (CF,SCAR, DL and Z), from ± 2.5 to ± 5 g kg-1. WSC techniques did not improve physical soil quality, but did significantly improve biological soil quality. A socio-economic survey indicated that the adoption of WSC techniques in the region is limited by manure shortage and a lack of specific erosion knowledge