Towards an ecological index for tropical soil quality based on soil macrofauna

The objective of this work was to construct a simple index based on the presence/absence of different groups of soil macrofauna to determine the ecological quality of soils. The index was tested with data from 20 sites in South and Central Tabasco, Mexico, and a positive relation between the model and the field observations was detected. The index showed that diverse agroforestry systems had the highest soil quality index (1.00), and monocrops without trees, such as pineapple, showed the lowest soil quality index (0.08). Further research is required to improve this model for natural systems that have very low earthworm biomass

Agronomic, economic and ecological aspects of the papaya (Carica papaya) production in Tabasco, Mexico

The cultivation of papaya is important in the tropic because it provides source of income to the farmer within a short time. Statistical data were obtained from farmers located in the Chontalpa, Rios and Centro-Sierra regions; the size of the survey was 67 farmers. The study shows the results of the farmers’ problem in a drastic reduction of their productivity because of the virosis and low prices in commercialization. The farmers were classified into three levels of technology, “low”, “middle” and “high”. The first one covers 88% of the farmers in seasonal conditions in contrast with the high technology that concentrates 4.5% in irrigation conditions. According to the technology used, the fertilizer shows more yields. Economically, the high technology had an internal tax return of 0.43 in comparison with the low technology of 0.25, which means that the investment is recovered with different yields. However, the use of high technology makes the system more competitive. Key words

Improving rainwater-use in Cabo Verde drylands by reducing runoff

Dryland agriculture in Cabo Verde copes with steep slopes, inadequate practices, irregular intense rain, recurrent droughts, high runoff rates, severe soil erosion and declining fertility, leading to the inefficient use of rainwater. Maize and beans occupy N80% of the arable land in low-input, low-yielding subsistence farming. Three collaborative field trialswere conducted in different agroecological zones to evaluate the effects ofwater-conservation techniques (mulching of crop residue, a soil surfactant and pigeon-pea hedges) combinedwith organic amendments (compost and animal or green manure) on runoff and soil loss. During the 2011 and 2012 rainy seasons, three treatments and one control (traditional practice) were applied to 44- and 24-m2 field plots. A local maize variety and two types of beanswere planted. Runoff and suspended sedimentswere collected and quantified after each daily erosive rainfall. Runoff occurred for rainfalls≥50mm(slope b10%, loamy Kastanozem),≥60mm(slope≤23%, silt–clay–loam Regosol) and≥40mm(slope≤37%, sandy loam Cambisol). Runoffwas significantly reduced only with themulch treatment on the slope N10% and in the treatment of surfactant with organic amendment on the slope b10%. Soil loss reached 16.6, 5.1, 6.6 and 0.4 Mg ha−1 on the Regosol (≤23% slope) for the control, surfactant, pigeon-pea and mulch/pigeon-pea (with organic amendment) treatments, respectively; 3.2, 0.9, 1.3 and 0.1 Mg ha−1 on the Cambisol (≤37% slope) and b0. 2Mg ha−1 for all treatments and control on the Kastanozem(b10% slope). Erosion was highly positively correlated with runoff. Mulch with pigeon-pea combinedwith an organic amendment significantly reduced runoff and erosion fromagricultural fields on steep slopes, contributing to improved use of rainwater at the plot level. Sustainable land management techniques, such as mulching with pigeon-pea hedges and an organic amendment, should be advocated and promoted for the semiarid hillsides of Cabo Verde prone to erosion to increase rainwater-use and to prevent further soil degradation

Soil and water pollution in a banana production region in tropical Mexico

The effects of abundant Mancozeb (Mn, Zn— bisdithiocarbamate) applications (2.5 kg ha-1week-1 for 10 years) on soil and surface-, subsurface- and groundwater pollution were monitored in a banana production region of tropical Mexico. In soils, severe manganese accumulation was observed, wheras the main metabolite ethylenethiourea was near the detection limit. Surface and subsurface water was highly polluted with ethylenethiourea, the main metabolite of Mancozeb (22.5 and 4.3 lg L-1, respectively), but not with manganese. In deep ground water, no ethylenethiourea was detected. The level of pollution in the region presents a worrisome risk for aquatic life and for human health

Soil and water conservation strategies and impact on sustainable livelihood in Cape Verde – Case study of Ribeira Seca watershed

Cape Verde, located off the coast of Senegal in western Africa, is a volcanic archipelago where a combination of human, climatic, geomorphologic and pedologic factors has led to extensive degradation of the soils. Like other Sahelian countries, Cape Verde has suffered the effects of desertification through the years, threatening the livelihood of the islands population and its fragile environment. In fact, the steep slopes in the ore agricultural islands, together with semi-arid and arid environments, characterized by an irregular and poorly distributed rainy season, with high intensity rainfall events, make dryland production a challenge. To survive in these fragile conditions, the stabilization of the farming systems and the maintenance of sustainable yields have become absolute priorities, making the islands an erosion control laboratory. Soil and water conservation strategies have been a centerpiece of the government0s agricultural policies for the last half century. Aiming to maintain the soil in place and the water inside the soil, the successive governments of Cape Verde have implemented a number of soil and water conservation techniques, the most common ones being terraces, half moons, live barriers, contour rock walls, contour furrows and microcatchments, check dams and reforestation with drought resistant species. The soil and water conservation techniques implemented have contributed to the improvement of the economical and environmental conditions of the treated landscape, making crop production possible, consequently, improving the livelihood of the people living on the islands. In this paper, we survey the existing soil and water conservation techniques, analyze their impact on the livelihood condition of the population through a thorough literature review and field monitoring using a semi-quantitative methodology and evaluate their effectiveness and impact on crop yield in the Ribeira Seca watershed. A brief discussion is given on the cost and effectiveness of the techniques to reduce soil erosion and to promote rainfall infiltration. Finally, we discuss the critical governance factors that lead to the successful implementation of such strategy in a country with scarce natural resources

Effect of Inoculation with Rhizobacteria and Arbuscular Mycorrhizal Fungi on Growth and Yield of Capsicum chinense Jacquin

We evaluated the effect of two rhizobacteria (Azotobacter chroococcum and Azospirillum brasilense) and a commercial product containing multiple strains of arbuscular mycorrhizal fungi (AMF) and an NPK fertiliser on the growth and yield of habanero chilli (Capsicum chinense Jacquin). All treatments were applied as single or combined inoculants, under nursery and field conditions, in a completely randomised design. The biofertilisers were applied to the roots by coating or dipping, with the inoculants in a solid or liquid support, respectively. At 30 days after inoculation, populations of 2.5×106 to 1.3×106 cfu g soil−1 of A. brasilense and 10.3×105 to 2.6×105 of A. chroococcum were detected in the rhizosphere of the crop. The prevalence of colonisation of plants inoculated with AMF ranged from 35 to 57%, with the greatest values recorded for the treatment involving single biofertilisation by root coating. In the nursery phase, single biofertilisation promoted a higher growth and nutrient content in the crop than combined biofertilisation. However, in the field phase the combined biofertilisation increased the nutrient content of the plant leaves, which was significantly greater than observed in the NPK treatment. The highest yields were recorded for the treatments involving a single inoculation of A. chroococcum and for those with the multi-strain of AMF, with average values of 2.5 and 2.3 kg plant−1 respectively, compared with 1.0 kg plant−1 obtained with the treatment in which NPK fertiliser was applied

Comparisons of Production Costs and Profit of Three Different Technology Levels of Papaya Production in Tabasco, Mexico

The survey was carried out from September 2006 to January 2007 in three papaya production sites located in main papaya production zones in Tabasco; SE Mexico. There are differences in size of the cultivated area, in the yield of the papaya as well as in production costs and profit, according to the different technology levels in the farming systems: low, medium and high technology cultivation level. The financial evaluations were carried out in three sites with different productive technologies. The comparison of the agronomic and economic traits results for low technology level in: V AN of 2359.00 USD, BCR in 1.9 and an equilibrium point of 3750.00 USD, TIR of 0.25. In order to avoid loses, a quantity of 10714 kg papaya should be sold. In medium technology VAN is 1605.10 USD, BCR is 1.7, TIR 0.20 and the equilibrium point is 12800.00 USD. 36571 kg of papaya should be yearly sold. In high technology level VAN is 11749.40, BCR is 2.73, TIR 0.43 and the equilibrium point is 12187.50 USD, 34821 kg papaya should be sold yearly. The indicators showed that all three levels are profitable and economically viable

Impact of climate change and anthropogenic activities on stream flow and sediment discharge in the Wei River basin, China

Reduced stream flow and increased sediment discharge are a major concern in the Yellow River basin of China, which supplies water for agriculture, industry and the growing populations located along the river. Similar concerns exist in the Wei River basin, which is the largest tributary of the Yellow River basin and comprises the highly eroded Loess Plateau. Better understanding of the drivers of stream flow and sediment discharge dynamics in the Wei River basin is needed for development of effective management strategies for the region and entire Yellow River basin. In this regard we analysed long-term trends for water and sediment discharge during the flood season in the Wei River basin, China. Stream flow and sediment discharge data for 1932 to 2008 from existing hydrological stations located in two subcatchments and at two points in the Wei River were analysed. Precipitation and air temperature data were analysed from corresponding meteorological stations. We identified change-points or transition years for the trends by the Pettitt method and, using double mass curves, we diagnosed whether they were caused by precipitation changes, human intervention, or both. We found significant decreasing trends for stream flow and sediment discharge during the flood season in both subcatchments and in the Wei River itself. Change-point analyses further revealed that transition years existed and that rapid decline in stream flow began in 1968 (P <0.01), and that sediment discharge began in 1981 (P <0.01) in the main river. In the two subcatchments, the transition years were 1985 (P <0.01) and 1994 (P <0.05) for water discharge, and 1978 and 1979 for sediment discharge (P <0.05), respectively. The impact of precipitation or human activity on the reduction amount after the transition years was estimated by double mass curves of precipitation vs. stream flow (sediment). For reductions in stream flow and sediment discharge, the contribution rate of human activity was found to be 82.80 and 95.56%, respectively, and was significantly stronger than the contribution rate of precipitation. This evidence clearly suggests that, in the absence of significant decreases in precipitation, strategies for managing the region need to focus on human activities to control erosion without restricting stream flow

Factors affecting domestic water consumption in rural households upon access to improved water supply: insights from the Wei River Basin, China

Comprehensively understanding water consumption behavior is necessary to design efficient and effective water use strategies. Despite global efforts to identify the factors that affect domestic water consumption, those related to domestic water use in rural regions have not been sufficiently studied, particularly in villages that have gained access to improved water supply. To address this gap, we investigated 247 households in eight villages in the Wei River Basin where three types of improved water supply systems are implemented. Results show that domestic water consumption in liters per capita per day was significantly correlated with water supply pattern and vegetable garden area, and significantly negatively correlated with family size and age of household head. Traditional hygiene habits, use of water appliances, and preference for vegetable gardening remain dominant behaviors in the villages with access to improved water supply. Future studies on rural domestic water consumption should pay more attention to user lifestyles (water appliance usage habits, outdoor water use) and cultural backgrounds (age, education)