Available online 10 July 2008 Planting basins and ripper tillage practices are major components of the recently introduced conservation agriculture package that is being extensively promoted for smallholder farming in Zimbabwe. Besides pre- paring land for crop planting, these two technologies also help in collecting and using rainwater more effi- ciently in semi-arid areas. The basin tillage is being targeted for households with limited or no access to draught animals while ripping is meant for smallholder farmers with some draught animal power. Trials were established at four farms in Gwanda and Insiza in southernZimbabwe to determine soilwater contri- butions and runoff water losses from plots under four different tillage treatments. The tillage treatments were hand-dug planting basins, ripping, conventional spring and double ploughing using animal-drawn implements. The initial intention was to measure soilwater changes and runoff losses from cropped plots under the four tillage practices. However, due to total crop failure, only soilwater and runoff were mea- sured from bare plots between December 2006 and April 2007. Runoff losses were highest under conven- tional ploughing. Planting basins retained most of the rainwater that fell during each rainfall event. The amount of rainfall received at each farm significantly influenced the volume of runoff water measured. Runoff water volume increased with increase in the amount of rainfall received at each farm. Soilwater content was consistently higher under basin tillage than the other three tillage treatments. Significant dif- ferences in soilwater content were observed across the farms according to soil types from sand to loamy sand. The basin tillage method gives a better control of water losses from the farmers’ fields. The planting basin tillage method has a greater potential for providing soilwater to crops than ripper, double and sin- gle conventional ploughing practices.
Decline in soil productivity has led to development of new methods that can sustain crop production and pro- ductivity (Cattanio, 2012). There is evidence that woody leguminous tree species can be used to produce bio- mass and recycle nutrients in agroforestry systems, thus hastening soil fertility restoration (Imogie et al., 2008). Leguminous trees have beneficial effects on the soil physical and chemical properties, soil moisture content and retention by their litter deposition, root activity and changes in microclimate brought about by the leaf canopy (Arowolo, 2007; Cattanio, 2012). Notwithstanding these benefits, the use of short term rotational leguminous tree species in a conservation agriculture system of the semi-arid regions of Kenya is little known. This study was therefore carried out to investigate the effect of short term rotational leguminous tree species on soilwater retention in a semi-aridconservation agriculture system. In this study, we hypothesized that short term legu- minous tree species greatly improve water retention in both the lower and upper soil strata and improve soil bulky density through their influence on soil organic matter in a semi-aridconservation agriculture agroforestry system.
overstocking. In this regard, the involvement of the local population in anti-erosion management activities is an important prerequisite. Thus, the community should be educated as to the consequences of accelerated reservoir sedimentation. The soil erosion and control should minimize the amount of disturbed soil and improve tillage systems, prevent runoff by capturing it using waterconservation structures like deepened contours and infiltra- tion pits. The catchment should be conserved with vertiver grass across the slope to slow down runoff and con- struction of sediment ponds before the runoff reaches the reservoir. There are other land use activities that are increasing the rate of sediment transport into the reservoir like brick laying in the radius of 500 m in the upslope of the reservoir. These activities should stop to reduce sedimentation. The rate of sedimentation in Mutangi cat- chment if not attended to, will result in further compromise of the food security and increase the vulnerability of the community to water shortages.
Globally, a range of agronomic factors have been reported to have an impact on the performance of conservation agriculture (CA) and often determine its performance in relation to conventional agriculture (CONV). To assess this performance in Zimbabwe, 48 CA experiments were conducted by the International Crops Research Institute for the Semi-Arid Tropics in the semi-arid areas of southernZimbabwe from 2004 to 2010, to calculate the weighted mean difference (WMD) through meta-analytical methods. The two CA practices, planting basins (Basins) and ripper tillage (Ripper), were compared with CONV. It was hypothesised that CA results improved yield compared with CONV and that the effect of CA practices on yield is affected by soil type, rainfall amount and distribution and selected management practices, which included rates of inorganic fertilisers and manures and mulching. Basins were superior to CONV in 59% of the experiments and the overall effect was significant (p < 0.001). The effect of Ripper was non-significant. The hypothesis that CA practices result in improved maize grain yield over CONV was accepted for Basins. The WMD for experiments conducted on sandy soils was 0.365 t ha −1 for Basins and 0.184 t ha −1 for Ripper, and in both cases was significant (p < 0.05). For clay soils, only the WMD for Basins was significant. A higher rainfall regime (500–830 mm) resulted in a lower WMD for Basins (0.095 t ha −1 ) and Ripper (0.105 t ha −1 ) compared with 0.151 t ha −1 for Basins and 0.110 t ha −1 for Ripper under lower rainfall (320–500 mm). The overall effect of Basins under the higher rainfall regime was not significant. There was better yield performance for Basins when the rainfall was well distributed; the reverse was noted for the Ripper. The application of 10–30 kg ha −1 of N (micro-dose range) resulted in a higher WMD for Basins than zero N application. Without N application, the WMD of Basins was not significant. For zero manure application in Basins, the WMD was 0.043 t ha −1 compared with 0.159 t ha −1 when manure was applied. The application of mulch depressed the WMD in Basins by 44% and Ripper by 89%. The hypothesis that yield performance under CA is influenced by soil type, rainfall amount and distribution, inorganic fertiliser and manure application was accepted.
Many methods for estimation of evaporation losses from free water surfaces were reported and it can be divided into several categories including: empirical methods (e.g. Kohler et al., 1955), water budget methods (e.g. Shuttleworth, 1988), energy budget methods (e.g. Anderson, 1954), mass-transfer methods (e.g. Harbeck, 1962); and combination methods (e.g. Penman, 1948).
plowing gives good preparation of the seed-bed with weed free condition and high yield than direct seeding, due to the fact that weed manifestation was greater in direct seeding than the conventional method (Yalcin et al., 2005). However, Ali (1985) reported no effect of the types of plow on the yield of wheat and the density of weeds. The conventional sowing practices are one of the reasons for low crop yield in the country (Khan et al., 1990). To mechanize sowing operation, an appropriate drill should be used to places the seed and fertilizer in the zone of adequate moisture and at desired soil depths.
Water is one of the crucial natural endowments for survival of human beings in particular and for living things in general. It has been experienced that there is an increasing need of the cautious use of the limited fresh water resources, and sustaining and recharging the groundwater in different parts of the world from time to time. It is due to the fact that if appropriate measures cannot be taken up immediately, there will be occurrence of crisis and then it will be detrimental to the very survival of mankind. For these reasons, different measures have been taken to manage water resources in many semi-arid and arid parts of the world. Implementation of varied water harvesting techniques, storage and water recharging mechanisms are among the measures taken by actors working in water sector. There are several benefits and constraints which come from using different types of water harvesting technologies that it is important to familiarize the technologies to the contexts where they are suitable in terms of place, persons, and purpose. In other words, it is crucial to use water resources efficiently by applying varies water management techniques that could be promoting economic growth, reducing poverty, considering environmental sustainability, and considering socio-cultural issues that could come from the application of water management techniques. Thus, individuals, governmental or non-governmental bodies which are working in water harvesting issues should consider the situation from different dimensions before deciding to implement a specific type of technique.
heat transport equations were numerically solved using the Galerkin’s finite element method for the spatial discretization and using a fully implicit, backward difference approach for the temporal discretization. Plant root water uptake and soilwater flow were fully coupled and equations were solved si- multaneously at the same time step. The soil profile consid- ered in this study had a depth of 3 m, equal to that of the large lysimeter, and was divided into 38 nodes with a finer dis- cretization in the upper soil layers (1 cm) than in the lower soil layers (20 cm). The large lysimeter measurements, in- cluding soil moisture, soil temperature, ET, and soil evapora- tion were used to assess model performance. The validation of the soilwater balance closure within the root zone gave an additional test of the effectiveness of the extended STEM- MUS. In addition, since the estimation of crop growth pa- rameters could harbor uncertainties, a sensitivity test was im- plemented to explore how the simulation results varied with fluctuating precipitation and irrigation under different crop growth scenarios.
Chapter 9 by Marita Laukkanen and Phoebe Koundouri, present an analytical attempt to approximating the behavior of economic agents in groundwater extraction under two possible scenarios, namely co-ordination and no co-ordination between the agents. This is a formalized experiment to investigate the potential of organizing irrigated agricultural regions in irrigation divisions; i.e. to investigate whether social welfare can increase from implementing irrigation divisions in a water basin. This is an economic policy that could prove efficient in the implementation of the WFD. In particular, the authors analyse a game with N farmers that extract groundwater from a common aquifer of small storage capacity. Their aim is to compare the socially optimal, myopic and feedback extraction strategies, the latter arising from competitive interaction between extracting agents. The main extension to existing literature is that the authors consider heterogeneous farmers, facing uncertainty deriving from stochastic rainfall. The farmers differ in terms of their choice of irrigation technology, which results in different farmer-specific impact on the aquifer recharge rate. The implications of the different strategies on extraction rates, groundwater table levels and welfare attained, are illustrated via simulations based on data from the Kiti aquifer in Cyprus.
Petrie, B., Chapman, A., Midgley, A.P., arker, R., 2014. Risk, Vulnerability and Resilience in the Limpopo River Basin system: climate change, water and biodiversity – a synthesis. For the USAID Southern Africa “Resilience in the Limpopo River Basin” (RESILIM) program. oneWorld sustainable Investments, Cape Town, South Africa.
Le travail présenté consiste à déterminer l’effet des pratiques culturales sur la stabilité des agrégats du sol et l’accumulation de la MO dans les zones semi-arides marocaines. Nos résultats montrent que l’adoption des systèmes de SD a un effet potentiel de séquestration de la MO dans la couche superficielle du sol (0-5cm) sans appauvrissement des couches profondes, et que l’apport additionnel des résidus de récolte (couverture totale SD 100) a tendance à améliorer le niveau de carbone dans tous les agrégats du sol. Ces résultats indiquent qu’il y a effectivement un regain d’équilibre dans le sol en condition de non-labour qui se traduit par une résistance à la désagrégation par rapport au labour traditionnel quel que soit le test utilisé pour l’estimation de la stabilité structurale à l’eau. Nos données confirment aussi que la rotation blé continu affiche le meilleur taux de MO dans le sol et par conséquent elle a favorisé l’agrégation par rapport aux rotations incluant la jachère.
A comprehensive economic characterization of the water in the region requires first of all that the economic significance of water in the region is evaluated. This involves an assessment of the residential, industrial, agricultural and tourism water needs in the area. This will include information on the population connected to public water supply system vs those with self-supply, the total cropped area, cropping patterns, gross production and income of the farming population for the agricultural sector, and the total number of tourist days and employment and turnover in the tourism sector. The key economic drivers influencing pressures and water uses need to be determined including (a) the general socio-economic indicators such as population growth, income, and employment; (b) the key sector policies that significantly influencewater use (e.g., agricultural and environmental policies); (c) the development of planned investments likely to affect water availability; and (d) the implementation of future policies (environmental and other) that is likely to affect water use. These economic drivers will need to be accounted in a dynamic perspective, i.e., to determine how these are likely to evolve over time. The final component of the economic characterization of water in a region is the application of appropriate methodologies to assess sector-specific water demand. This involves deriving the marginal value of water in consumption and production, the price and income elasticity of demand, the marginal and average willingness to pay for public goods and quality changes of common access resources, and the associated risk parameters
To cope with the persistent droughts, 3% of the interviewed households were forced to fall back on savings, whilst 5% sold household goods that were accumulated over the preceding seasons. Had they accumulated much, the contribution of the two could have increased significantly as alternative sources of income to avert hunger and starvation. However, the average income contribution of savings and sale of household goods remained low because of extreme poverty. At the same time, resorting to savings and sale of asset holdings prevented many of the smallholder farmers to make large farm investments which could have reduced the impact of droughts. For example, one farmer who had acquired various farming equipment was compelled to sell them so as to purchase food. Therefore, the family food needs of that farmer were provisionally met, at the expense of improved tillage equipment. This meant that the family would be unable to produce food in the coming season even if there were normal to above normal rainfall. Comments similar to the ones below were made by a quarter of the interviewees, showing that the depletion of asset holdings which were induced by drought had negatively impacted on their welfare:
against the rainfall impact [7,10,11]. Consequently, ma- jor part of the rain that falls during the early part of sea- son on Alfisols, is often lost as runoff which in turn cau- ses appreciable soil loss and moisture stress . This shedding of water occurs even when the soil profile is relatively dry. Several approaches have been suggested to address the problem of poor infiltration during early part of the rainy season on SAT Alfisols. One such approach is to use the management systems viz. conservation till- age and others, which in the long-term could improve the Alfisol structure. Improved soil structure is expected to provide long-term solution to this problem of crusting and sealing on SAT Alfisols. However, most of the re- search findings with such management systems for SAT Alfisols have not been conclusive and also the possibility of adoption of such technologies by SAT farmers is ex- pected to be very low. The other approach to alleviate this problem on SAT Alfisols could be to till the soil in order to break the crusts and seals and loosen the top soil before it becomes too compact and hard. This paper dis- cusses the results from the experiments as well as simu- lation modeling on the effectiveness of various inter-row tillage systems in controlling runoff, soil loss and in in- creasing crop yields on Alfisols.
concentrations to increase in the soil solution . The adsorption is measured by shaking of the soil samples with standard phosphate solution, measuring the change in phosphate concentration and calculating the phosphate adsorbed. In solution, the concentration of phosphate is determined and the quantity of phosphate adsorbed is calculated. Freundlich and Langmuir adsorption isotherms models are mostly employed for understanding the relationship between the quantity of phosphorus adsorbed per unit soil weight and the concentration of phosphorus in solution and provide a distribution-equilibrium coefficient that describes the ratio of adsorbed to dissolved orthophosphates. They have previously been applied to a wide variety of soils , however none of which investigated P dynamics for the soils of Tunisia; in particular the soils of the Sahel region. This region is considered to be one of the most important areas for crop production in Tunisia. The aim of this study was to investigate the P adsorption capacity by three soil profiles from three different sites of
DOI: 10.4236/jep.2019.1010079 1335 Journal of Environmental Protection cultural Research Centre for International Development (CIRAD) . It is a holistic landscape level method for managing surface water on farmers’ fields, in which it decreases runoff, increases water infiltration and, therefore, captures rainfall close to the crop root system . Placing a field under CRT requires the construction of permanent ridges (using a topographic equipment: automatic level, water level etc.), about 100 cm wide, prior to crops planting. Then, the annual small ridges will be constructed along these permanent ridges following contour lines. When necessary, waterways to evacuate excess water off the fields may also be added to the works. So, the furrows become rain water infiltration area which could be of great advantage for crop. Consequently, when applied in Sudanian area (rainfall varying from 800 to 1200 mm) in southern Mali, where runoff still occurs in fields with a slope as low as 1% to 2% leading to crops yields increase of 30% to 50% for maize, sorghum, millet, groundnut and cotton .
A fundamental requirement for accurate irrigation scheduling is to determine crop water needs or crop evapotranspiration (ETc). The most common and practi- cal approach used for estimating crop evapotranspira- tion is the FAO-56 method published by the Food and Agricultural Organization (FAO) of the UN as FAO irri- gation and Drainage paper No. 56 . This approach has been widely used due to its simplicity and its applicabil- ity at operational basis with satisfying results under various climates and over several crops [8-18]. In addi- tion to the single crop coefficient (Kc) approach, FAO- 56 introduced dual crop coefficient procedure where the single Kc is separated into a basal crop coefficient, or Kcb (primary crop transpiration), and a soil evaporation coefficient (Ke). The FAO-56 dual procedure provides an excellent framework for calculating daily ETc. How- ever, successful application is highly dependent on the ability to derive an appropriate Kcb curve that matches the actual crop growth and ETc conditions that occur during a given season .
within the whole part of the soil profile during the direct seeding variant evaluation. This was prob- ably caused by the continuous macropore presence in the soil. In the case of ploughing, saturation of the ploughed profile with water, was found out the blue colour representation in the depth of 0.25–0.30 m being low. The infiltration decrease in that depth was probably caused by ploughing to the identical depth and by soil compacted layer occurrence below the furrow bottom. HANGEN et al. (2002) presents as the possible cause of these infiltration differences various methods of soiltillage: the homogeneous layer with horizontal structure is generated in the soil conventional tillage with ploughing and the vertical structure is generated during the soil reduced tillage. Sig- nificant for infiltration in this case are the vertical macro pores generated by the earthworms as well as the soil ruptures. These facts are reflected in the infiltration speed, nutrients elutriation, and water erosion. Some authors suggest that the reduced soiltillage offers an infiltration increase and at