Impact of conservation agriculture practices under a decade of tillage, crop rotation and crop residue management systems on selected soil physical properties and simulated soil erosion on a Haplic Plinthosol
| dc.contributor.advisor | Elephant, D.E. | |
| dc.contributor.author | Nonxuba, Shayne Cossy | |
| dc.date.accessioned | 2026-08-19T07:09:08Z | |
| dc.date.available | 2026-08-19T07:09:08Z | |
| dc.date.issued | 2024 | |
| dc.description | Msc dissertation | |
| dc.description.abstract | The effects of conservation agriculture (CA) are not instant but are gradually visible with time of implementation form short, medium to long term. Conventional agriculture and inappropriate agronomic practices by farmers especially small-scale growers (SSG) are common in the Eastern Cape Province. Government interventions or strategies to boost the implementation of CA have failed to yield desired results. This led to exacerbated soil degradation rates overtime, as soils of the Eastern Cape are highly susceptible to degradation due to their mineralogy of low organic matter, and shallow depth. The general aim of the study was to evaluate the effect of tillage management practices, crop rotations comprised of maize (Zea mays), wheat (Triticum aestivum) and soybean (Glycine max) crops associated with different crop residue management practices on selected soil physical properties and soil erosion by water through runoff and soil loss after a decade of CA in the Phandulwazi ecotope. The specific objectives of the study were to (i) investigate the effect of tillage, crop rotation and crop residue management practices after a decade of CA on selected soil physical parameters, (ii) simulate the effect of tillage, crop rotation and crop residue management practices after a decade of CA on soil loss and runoff. The evaluation was done on a CA field trial that began in 2012 and still on-going. The experiment was designed in a split split-plot trial structure with 3 replicate blocks comprised of 16 treatment combinations. The main, sub and sub-sub plots were allocated to tillage [no-tillage (NT) and conventional tillage (CT)], crop diversification [maize-fallowmaize (MFM); maize-fallow-soybean (MFS); maize-wheat-maize (MWM); maize-wheatsoybean (MWS)] and crop residue management [retention (R+)], respectively. Soil samples from 0 – 10, 10 – 20 and 20 – 30 cm depths were collected from the CA trial after twenty-three (23) cropping seasons (2012 –2023/24). Significant responses were observed mostly on NT plots subjected to rotation of MWM and MWS crops. Soil physical properties [bulk density (BD), particle density (Ps), mass wetness ( m), volumetric water content ( v), porosity ( ), saturated hydraulic conductivity (Ks), mean weight diameter dry & wet (MWDdry & MWDwet), and stability index (SI)] were affected by CA strategies in the medium term (+ten years). Tillage practices showeda dominant significant effect (NT plots greatly improved soil physical properties than CT) over crop rotations and residue management on BD, and aggregate stability (AGS). Soybean rotation treatments (MFS and MWS) had a significant effect on BD and AGS(i.e. it reduced BD and enhanced AGS), likely due to the quick decomposition of soybean residues, indicating potential improvements in soil health and soil quality with legume inclusion in rotations. Additionally, residuesubstantial amount of SOM returned by residue decomposition. There were no significant differences observed in Ks, which could be attributed to the nature of the particle size distribution, as water moves more easily on sandy soils. These medium-term results present continuous benefits from proper implementation of CA in sustainable farming and resource conservation. Soil loss and runoff were low for all treatment plots under no-tillage system as the practice reduces soil erosion that is caused by tillage farming, especially in sandy loam soils. Runoff and soil loss were both significantly higher in MFM (subplot subjected to monocropping) followed by MFS (subplot under rotation of two crops) and lowest in MWS (subplots under crop rotations of three crops). Residue retained treatment plots registered low soil loss & runoff because of better soil structure and aggregation as the binding products (formed during decomposition) merge soil particles, thereby reducing sediment deployment. These results signify CA benefits in soil conservation and sustainable farming for the present and future agricultural produce. Moreover, this study correlated soil properties with soil loss and runoff thereby elucidating significant role played by soil structural indices on soil erodibility. BD and m predicted soil loss with high correlation coefficient (R2 ) and low root mean square error (RMSE); thus, suggesting a strong reliability. Further evaluation and validation of the developed model however remains crucial. Investigation of soil erosion and measuring nutrient loss within sediment deposition is ideal for future studies. | |
| dc.identifier.citation | Nonxuba, C.S. (2024) Impact of conservation agriculture practices under a decade of tillage, crop rotation and crop residue management systems on selected soil physical properties and simulated soil erosion on a Haplic Plinthosol. MSc Agriculture (Soil Science) dissertation. Alice, South Africa: University of Fort Hare. | |
| dc.identifier.uri | http://hdl.handle.net/20.500.11837/4949 | |
| dc.language.iso | en | |
| dc.publisher | University of Fort Hare | |
| dc.subject | Soil degradation | |
| dc.subject | Soil erosion | |
| dc.subject | Soil conservation | |
| dc.title | Impact of conservation agriculture practices under a decade of tillage, crop rotation and crop residue management systems on selected soil physical properties and simulated soil erosion on a Haplic Plinthosol | |
| dc.type | Thesis | |
| person.identifier.orcid | 0000-0002-3222-5891 |