Land and Soil Capability - Case Study Example

Introduction and conceptual framework There is need to put into consideration on-site and off-site impacts in the process of assessment of land and soil capability (LSC). The impact that results from lack of management of the limitations should also be put into consideration. A good example is the case of marginal cropping land, where as a result of lack of management of water erosion limitation; there is significant water erosion that degrades soil on-site, which would lead to sedimentation and turbidity off-site. However on this type of land, water erosion limitation can be put to control use of acceptable land management practices which are readily available. There is need to put into consideration the cost, technology and management practices so as to overcome the limitations. Theoretically most limitations can be addressed by putting enough resources and technology, even though this often not realistic option with the exception in the most productive land uses. In the development of the definition of the LSC classes it is important to put into consideration the biophysical features of the land when deriving LSC class that are linked to the hazards and the way hazards are to be managed. For high LSC classes there are greater limitations in land use involved and thus calling for more inputs, expertise and investment level so as to achieve the desired land sustainability. In some instances, there may be very severe limitations which may not be taken care of by use of any level of input. Since the time the original rural land capability classification was published, a lot of development has been seen in both cropping and grazing management (Emery 1986). Some of the practices that have emerged in cropping include new stubble management, controlled traffic, direct drilling, pasture cropping and raised beds. On the other hand grazing has seen development such time controlled grazing, strategic grazing, rotational grazing and cell grazing in addition to using perennial grasses more widely. Whether all the innovation practices fit in the new LSC assessment scheme it is a debatable with quantification yet to be made with more field experience being needed to address some of the issues. The assessment are guided by how effective the practices in managing and controlling the hazards, and the inputs , expertise and investment level required in effective implementation of the practices. There are also There are also other landscape limitations other than the ones which have been pointed out in the scheme which are of relevance when determining the agricultural potential of the land and soil. These have influence on the level of agricultural production as opposed how susceptible the land is to degradation and thus can also be determining factors on what use the land will be put to. This limitations are moisture stress limitations –this is dependant on climate and the water holding capacity of soil fertility –depends on abundance of nutrients in the soil in terms of the major and trace elements, cation exchange capacity of the soil, its leaching potential and soil chemistry (which in presence of carbonates pH, phosphorus absorption capacity,) (Sanchez et al. 2003) Land capability LCS and RT in Blackville region have been identified to be factors which play a significant role due to several reasons (Van Gool, Tille & Moore (2005). The use to which the land is to put to, permanent features of the land including erosion risk, the slope, the workability of soil are important in Blackville region. Secondly, with land qualities having been assigned to the region land unit land capability rating can be provided for each of the land units by the land requirements being matched to the land use. In addition a wide land uses will be a reflection of common management practices (Grose ,1999). By use of land capability rating that is based on the kind of land use between the change in land use and the management practices incorporated in the land use is useful in understanding the interaction. For regular cultivation and for grazing ranking of LCS is based on the level of severity of limitation which are likely to have effect on the land uses as can be seen in Figure 1. Figure 1 The severity range from limited (L), moderate (M), intense (I). Depending on suitability for a range of agricultural activities LCS classification of land falls into 5 classes as can be seen in table 1. The recommendation by Atlas of New South Wales (2012) is that higher LCS classes need to be given high levels of inputs. Emphasis is also laid on the land being used optimally as opposed to maximum use of land. Table 1 Class 1 was found by Hulme et al. (2002) and this class does not have any major limitation and constrains and is described as being arable land. Grove (1999) recommendation is that the land class1 is suitable for a variety of cultivation and grazing activities. With average climatic conditions Class 1 is of high productivity and has capability of being collected without there being a risk of harming the soil resources of loss of productivity of the soil Murphy et al. (2004) and Hulme et al. (2002) reported on Class II (C-II). This class of land when considered for regular cultivation of crops is described as being arable and suitable but when the use is continuous there will be minor to moderate constraints. The observation made by George (2000) the environmental constaints is likely to bring about reduction in production and there may be need for rotation in sown pastures. Through proper management and with some conservation measures being taken the limitations associated with this class can be taken care of. In the fair capability class, there is moderate physical limitations that have a significant effect on the productivity of the land utilization or risk of land degradation. In this class there is to have careful planning and taking conservation measures. From class III(fair capability) the next class is the low capability(Class IV) where there is a high degree of physical limitations which are not easy to overcome by use of standard development techniques and resulting to high risk of land degradation and thus calling for extensive conservation requirements. The last class is the very low capability (Class V) where severity of physical limitation is such that its use is prohibited owing to either the development cost or the associated risk of land degradation. According to Gross (1999), it is possible to reduce the limitations considerably by use of soil conservation measures and use land management practices. For land use type classification and other characteristics, the criteria used in the defining of the land classes incorporate both economic and social biophysical factors. Table 4 gives land capability RT for Blackville area. Table 2 Diagnostic criteria C-1(BEST) C-II C-III C-IV C-V(WORST) Slope (%) 0 -5 5-8 8 -18 18-27 >27 Site drainage Excessively well drained Moderately well drained Imperfectly drained Poorly drained Very poorly drained Rooting depth(cm) Very shallow(VS)150 Soil workability Very good (VG) Good (G) Fair (F) Poor (P) Very poor (VP) Salinity hazard No hazard (NR) Partial or low hazard (PR) Moderate hazard(MR) High hazard(HR) Saline land(PS) Surface soil structure decline Very low (VL) Low(L) Moderate (M) High (H) Very High (VH) Ph at 0-10 and 50-80cm depth Strongly acid (Sac) Moderaly acid (Mac) Neutral (N) Moderately alkaline (Malk) Strongly alkaline (Salk) Water erosion hazard Very low (VL) Low(L) Moderate (M) High (H) Very High (VH) Waterlogging Very low (VL) Low(L) Moderate (M) High (H) Very High (VH) Flood hazard Very low (VL) Low(L) Moderate (M) High (H) Very High (VH) According to land classification aerial photo Blackville region has been put into 8 land units which are: I1, II2, II3, III2, III3, IV2, IV3 and V2. Below in the table listed land capability classification (Table 3, 4 & 5 and Figure 2). Table 3 Land Unit I1 V2 Diagnostic criteria Value Class rating Value Class rating Slope (%) 5-7 C-II 0-3 C-1 Site drainage Moderately well drained C-11 Very poorly drained C-V Rooting depth(cm) Shallow (S) 15-20 C-11 Deep (D) 80-100 C-IV Soil workability Fair(f) C-III Poor(P) C-IV Salinity hazard Partial or low hazard (PR) C-II Moderate Hazard(MR) C-III Surface soil structure decline Low(l) C-II Moderate (M) C-IV Ph at 0-10 and 50-80cm depth Moderately acid(Mac) C-II Moderately alkaline(Malk) C-IV Water erosion hazard Moderate (M) C-III Low (l) C-II Waterlogging Moderate (M) C-III High (H) C-IV Flood hazard Moderate (M) C-III Very low (VL) C-I Overall class rating C-II Overall class rating C-IV Table 4 Land Unit II2 AND II3 III2 AND III3 Diagnostic criteria Value Class rating Value Class rating Slope (%) 11-20 C-IV 20-25 C-1V Site drainage Moderately well drained C-11 Excessively well drained C-I Rooting depth(cm) Moderate (M) 30-50 C-III Moderate (M) 30-50 C-III Soil workability Fair(F) C-III Poor(P) C-IV Salinity hazard High hazard (HR) C-IV High Hazard(HR) C-IV Surface soil structure decline Moderate (M) C-III High (H) C-IV Ph at 0-10 and 50-80cm depth Moderately alkaline(Malk) C-IV Moderately alkaline(Malk) C-IV Water erosion hazard Moderate (M) C-III High (l) C-IV Waterlogging Moderate (M) C-III High (H) C-IV Flood hazard Very low (VL) C-III Very low (VL) C-I Overall class rating C-III Overall class rating C-IV Table 5 Land Unit IV2 IV3 Diagnostic criteria Value Class rating Value Class rating Slope (%) 25-30 C-V 25-30 C-V Site drainage Excessively well drained C-1 Excessively well drained C-I Rooting depth(cm) Deep (D) 100-120 C-IV Deep (D) 100-120 C-IV Soil workability Poor(P) C-IV Poor(P) C-IV Salinity hazard High hazard (HR) C-IV High Hazard(HR) C-IV Surface soil structure decline Very high(VH) C-V Very High (VH) C-V Ph at 0-10 and 50-80cm depth Moderately alkaline(Malk) C-IV Neutral (N) C-III Water erosion hazard Very high(VH) C-V Very high(VH) C-V Waterlogging Moderate (M) C-III High (H) C-IV Flood hazard Very low (VL) C-I Very low (VL) C-I Overall class rating C-IV Overall class rating C-IV Figure 2 Conclusion Li et al (2012) has demonstrated that land database for Blackville area is of high importance by use of the LCS above, with the data connecting the individual soil kind and their characteristics being important for the efficiency of the scheme. The capability classification depends on the use of the land. The limitations of the soil, the native weather and the land management constrains. Land capability mapping process need to be done by a person who has a lot of experience in natural supply techniques in addition to having residential information. References Brown, I., Poggio, L., Gimona, A., & Castellazzi, M. (2010). Climate change, drought risk and land capability for agriculture: implications for land use in Scotland. Regional Environmental Change, 11(3), 503-518. doi: 10.1007/s10113-010-0163-z Central West CMA 2008. Land and Soil Capability – How we safely manage the land. Land classifications of the Central West – 2008. Central West Catchment Management Authority, Wellington, NSW. Cunningham, G. M., Higginson, F.R., Riddler, A.M.H., & Emery K.A. (1988). System used to classify rural land in New South Wales. Dent D and Young A 1981. Soil survey and land evaluation. George Allen & Unwin, London. Jansen, L. J. M, Gregorio, A. D. (2002). Parametric land cover and land-use classifications as tools for environmental change detection. Agriculture, Ecosystems and Environment ,91, 89–100. Doi: S0167-8809(01)00243-2 FAO 1976. A framework for land evaluation, Soils Bulletin 32. Food and Agriculture Organization of the United Nations, Rome. Kay BD 1990. Rates of change of soil structure under different cropping systems. Advances in Soil Science 12, 1–52. Li, Z., Huffman, T., Zhang, A., Zhou, F., & McConkey, B. (2012). Spatially locating soil classes within complex soil polygons – Mapping soil capability for agriculture in Saskatchewan Canada. Agriculture, Ecosystems & Environment,152, 59-67. doi: 10.1016/j.agee.2012.02.007 USDA 1983. National agricultural land evaluation and site assessment. Soil Conservation Service, US Department of Agriculture, Washington DC. McKenzie NJ, Henderson B and McDonald WS 2002. Monitoring soil change: Principles and practices for Australian conditions, Land and Water Technical Report 18/02. CSIRO, Canberra. Murphy, B.W., Murphy, C., Wilson, B.R., Emery, Lawrie, K.A., Bowman, J., G., Lawrie, R.& Erskine, W. (2004). A revised land and soil capability classification for New South Wales. Conserving Soil and Water for Society:Sharing Solutions, No. 1010,p.1-4. Rosa, D. & Diepen, C. A. (2002). Land use, land cover and soil sciences. Vol. II Qualitative and Quantitative Land Evaluations. Encyclopedia of Life Support Systems.p.307-326. Singer, M. J. (2006). Land Capability Analysis. Encyclopedia of Soil Science. p.959-961.DOI: 10.1081/E-ESS-120001827. Read More