Your search found 5 records
1 Odeh, I. O. A.; Onus, A. 2004. Spatio-temporal modelling of soil acidity in a semi-arid region of Australia. In Eswaran, H.; Vijarnsorn, P.; Vearasilp, T.; Padmanabhan, E. (Eds.). Innovative techniques in soil survey: Developing the foundation for a new generation of soil resource inventories and their utilization. Bangkok, Thailand: Land Development Department. pp.299-315.
(Location: IWMI-HQ Call no: 631.4 G000 ESW Record No: H037567)
2 Noble, Andrew; Ruaysoongnern, S.; Sukchan, S.; Berthelsen, S. 2004. Role of soil resource data in assessing soil acidification risk: An example from Northeast Thailand. In Eswaran, H.; Vijarnsorn, P.; Vearasilp, T.; Padmanabhan, E. (Eds.). Innovative techniques in soil survey: Developing the foundation for a new generation of soil resource inventories and their utilization. Bangkok, Thailand: Land Development Department. pp.333-340.
(Location: IWMI-HQ Call no: 631.4 G000 ESW Record No: H037569)
3 Wijewardena, J. D. H. 2001. Effect of sources and levels of liming materials on soil acidity in ultisols of the upcountry. Annals of the Sri Lanka Department of Agriculture, 3:365-372.
Soil properties ; Dolomite ; Soil ph ; Acrisols ; Vegetables ; Organic fertilizers / Sri Lanka / Bandarawela
(Location: IWMI-HQ Call no: P 7671 Record No: H039443)
4 Armour, J. D.; Berthelsen, S.; Ruaysoongnern, S.; Moody, P. W.; Noble, Andrew D. 2005. Remediation of soil acidification by form of nitrogen fertilizer on grass swards of Australia and Thailand. In International Union of Soil Sciences (IUSS); Institut de Recherche pour le Developpement (IRD); Thailand. Land Development Department (LDD); International Water Management Institute (IWMI); FAO. Regional Office for Asia and the Pacific (FAO RAP); Khon Kaen University. Faculty of Agriculture. Management of tropical sandy soils for sustainable agriculture: a holistic approach for sustainable development of problem soils in the tropics. Proceedings of the First Symposium on Management of Tropical Sandy Soils for Sustainable Ariculture, Khon Kaen, Thailand, 27 November – 2 December 2005. Bangkok, Thailand: FAO Regional Office for Asia and the Pacific (FAO RAP). pp.135-139.
Soil profiles ; Acidification ; Grasses ; Pastures ; Species ; Cropping systems ; Nitrogen fertilizers ; Soil pH ; Alkalinity ; Acrisols / Australia / Thailand / Mareeba / Tully / Chiang Yuen
(Location: IWMI HQ Call no: 630 G000 INT Record No: H047325)
(0.36 MB) (16.9 MB)
Acidification of soil profiles from legume and N fertilized crops is a serious sustainability threat. Under tropical conditions of Northeast Thailand and Northern Australia, acidification to >90 cm has been recorded in Stylosanthes and Leucaena based pasture systems. Acidification has also been measured in other Australian cropping systems fertilized with urea or ammonium forms of N. The major processes contributing to what could be termed anthropogenic acidification are removal of base cations in the harvested product and leaching below the root zone of nitrate from ammonium and urea N fertiliser or legumes resulting in an accumulation of protons in surfaces horizons. If prophylactic applications of lime are not undertaken, acid generation in surface horizons will progressively move down the profile inducing subsoil acidification. Subsoil acidity is often difficult to correct using conventional applications of liming products. Field experiments with pastures on Acrisols in Northeast Australia (two sites) and Northeast Thailand (one site) compared the rates of alkalisation or acidification from N applied as nitrate or as urea (Australia) or ammonium sulphate (Thailand). Soil pH increased where N was applied as nitrate and decreased where N was applied as urea or ammonium sulphate. At one of the sites in Australia, regular applications of N as nitrate at 350 kg N ha-1 year-1 were made to irrigated Digitaria melanjiana cv Jarra. This significantly increased soil pH (1:5 0.01 M CaCl2) by up to 0.5 units to a depth of 0.90 m over a period of 4 years when compared to bare soil. The alkalisation of the profile was equivalent to 2.7 t/ha of calcium carbonate distributed evenly down the profile. Urea at the same rate of N decreased soil pH at 20-50 cm by 0.2 units. Similar but smaller changes were measured at the other Australian site (Brachiaria decumbens) and the site in Thailand (Andropogon gayanus cv Carimagua (Gamba grass). Treatment effects at these sites were restricted by time (1 year) or seasonal conditions that limited the number of N applications that could be applied (290 kg N/ha over 3 years) at the Thai site. The research has clearly demonstrated that nitrate N fertilizer can rapidly correct soil acidity down the soil profile to 0.9 m and this is attributed to the release of alkali from roots as nitrate is taken up. Such a strategy may be an effective approach to addressing subsoil acidification where surface applications of lime are ineffective and profile modification is cost prohibitive.
5 Berazneva, J.; McBride, L.; Sheahan, M.; Guerena, D. 2018. Empirical assessment of subjective and objective soil fertility metrics in East Africa: implications for researchers and policy makers. World Development, 105:367-382. [doi: https://doi.org/10.1016/j.worlddev.2017.12.009]
Soil fertility ; Agricultural productivity ; Soil analysis ; Soil pH ; Soil types ; Soil quality ; Cation exchange capacity ; Natural resources management ; Researchers ; Policy making ; Farmers attitudes ; Crop yield ; Maize / East Africa / Kenya / Tanzania
(Location: IWMI HQ Call no: e-copy only Record No: H048769)
(1.09 MB)
Bringing together emerging lessons from biophysical and social sciences as well as newly available data, we take stock of what can be learned about the relationship among subjective (reported) and objective (measured) soil fertility and farmer input use in east Africa. We identify the correlates of Kenyan and Tanzanian maize farmers’ reported perceptions of soil fertility and assess the extent to which these subjective assessments reflect measured soil chemistry. Our results offer evidence that farmers base their perceptions of soil quality and soil type on crop yields. We also find that, in Kenya, farmers’ reported soil type is a reasonable predictor of several objective soil fertility indicators while farmer-reported soil quality is not. In addition, in exploring the extent to which publicly available soil data are adequate to capture local soil chemistry realities, we find that the time-consuming exercise of collecting detailed objective measures of soil content is justified when biophysical analysis is warranted, because farmers’ perceptions are not sufficiently strong proxies of these measures to be a reliable substitute and because currently available high-resolution geo-spatial data do not sufficiently capture local variation. In the estimation of agricultural production or profit functions, where the focus is on averages and in areas with low variability in soil properties, the addition of soil information does not considerably change the estimation results. However, having objective (measured) plot-level soil information improves the overall fit of the model and the estimation of marginal physical products of inputs. Our findings are of interest to researchers who design, field, or use data from agricultural surveys, as well as policy makers who design and implement agricultural interventions and policies.
Powered by DB/Text WebPublisher, from
