Assessment of tillage effects on soil quality of pastures in South Africa with indexing methods

Abstract

Soil quality of pastures changes through time because of management practices. Excessive soil disturbance usually leads to the decline in soil quality, and this has resulted in concerns about kikuyu (Pennisetum clandestinum)–ryegrass (Lolium spp.) pasture systems in the southern Cape region of South Africa. This study aimed to understand the effects of tillage on soil quality. The soil management assessment framework (SMAF) and the locally developed soil quality index for pastures (SQIP) were used to assess five tillage systems and were evaluated at a scale inclusive of variation in topography, pedogenic characteristics and local anthropogenic influences. Along with assessment of overall soil quality, the quality of the physical, chemical and biological components of soil were considered individually. Soil physical quality was largely a function of inherent pedogenic characteristics but tillage affected physical quality adversely. Elevated levels of certain nutrients may be warning signs to soil chemical degradation; however, tillage practice did not affect soil chemical quality. Soil disturbance and the use of herbicides to establish annual pastures has lowered soil biological quality. The SQIP was a more suitable tool than SMAF for assessing soil quality of high-input, dairy-pasture systems. SQIP could facilitate adaptive management by land managers, environmentalists, extension officers and policy makers to assess soil quality and enhance understanding of processes affecting soil quality.

Variations on soil carbon dioxide flux with land-use type and selected soil properties in the hardveld of Botswana

“…Similarly, non-significant changes in C content with land use were observed for CTL, GRL and HL (Table 2). This finding is also supported by Swanepoel et al (2015), who stated that soil quality, in particular soil OC, changes over time because of management practices, especially tillage.…”

“…In a study of savanna ecosystems in Botswana, Kgosikoma et al (2015) observed a strong dependency of soil OC on rainfall and herbaceous biomass, which has a profound effect on biological crust formation (Thomas et al 2011). Furthermore, Swanepoel et al (2015) noted that soil quality, particularly soil OC, changes through time because of management practices, especially tillage. For instance, cultivation was reported to have depleted former virgin soils of humic substances across semi-arid agro-ecosystems in South Africa with a potential of reducing C and nitrogen losses into the atmosphere (Kotzé et al 2016).…”

Tillage effects, soil quality and production potential of kikuyu–ryegrass pastures in South Africa

“…(, , ) have identified physical, chemical and biological indicators that have a functional role in pasture systems in South Africa. Subsequently, a selection of seven soil quality indicators that conveyed the most useful information for determining soil quality status was determined (Swanepoel et al ., ) and evaluated (Swanepoel et al ., ). However, these studies did not relate soil properties to herbage yield.…”

Soil Quality Evaluation Using the Soil Management Assessment Framework (SMAF) in Brazilian Oxisols with Contrasting Texture

“…The SMAF has also been successfully used in several other countries around the world [e.g., South Africa (Swanepoel et al, 2015), Ethiopia (Gelaw et al, 2015), Nepal (Kalu et al, 2015)]. The first SMAF application to Brazilian tropical soils was conducted by Cherubin et al (2016a), who verified that SMAF was effective for assessing SQ changes due to land-use change (LUC) for sugarcane expansion in the central-southern region.…”