Extent of Soil Acidity in No-Tillage Systems in the Western Cape Province of South Africa

Roughly 90% of farmers in the Western Cape Province of South Africa have converted to no-tillage systems to improve the efficiency of crop production. Implementation of no-tillage restricts the mixing of soil amendments, such as limestone, into soil. Stratification of nutrients and pH is expected. A soil survey was conducted to determine the extent and geographical spread of acid soils and pH stratification throughout the Western Cape. Soil samples (n = 653) were taken at three depths (0–5, 5–15, 15–30 cm) from no-tillage fields. Differential responses (p ≤ 0.05) between the two regions (Swartland and southern Cape), as well as soil depth, and annual rainfall influenced (p ≤ 0.05) exchangeable acidity, Ca and Mg, pH(KCl), and acid saturation. A large portion (19.3%) of soils (specifically in the Swartland region) had at least one depth increment with pH(KCl) ≤ 5.0, which is suboptimal for wheat (Triticum aestivum), barley (Hordeum vulgare), and canola (Brassica napus). Acid saturation in the 5–15 cm depth increment in the Swartland was above the 8% threshold for production of most crops. Acid soils are a significant threat to crop production in the region and needs tactical agronomic intervention (e.g. strategic tillage) to ensure sustainability.

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Rainfall and river flow trends for the Western Cape Province, South Africa

South African Journal of Science ◽

10.17159/sajs.2019/6028 ◽

2019 ◽

Vol 115 (9/10) ◽

Cited By ~ 1

Author(s):

Rakhee Lakhraj-Govender ◽

Stefan W. Grab

Keyword(s):

Climate Change ◽

South Africa ◽

River Flow ◽

Supply And Demand ◽

Temporal Distribution ◽

Annual Rainfall ◽

Western Cape ◽

Western Cape Province ◽

Winter Rainfall ◽

Intergovernmental Panel

Climate change has the potential to alter the spatio-temporal distribution of rainfall, subsequently affecting the supply and demand of water resources. In a water-stressed country such as South Africa, this effect has significant consequences. To this end, we investigated annual and winter rainfall and river flow trends for the Western Cape Province over two periods: 1987–2017 and 1960–2017. Annual rainfall for the most recent 30-year period shows decreasing trends, with the largest magnitude of decrease at the SA Astronomical Observatory rainfall station (-54.38 mm/decade). With the exception of the significant decreasing winter rainfall trend at Langewens (-34.88 mm/decade), the trends vary between stations for the period 1960–2017. For the period 1987–2017, statistically significant decreasing winter trends were found at four of the seven stations, and range from -6.8 mm/decade at Cape Columbine to -34.88 mm/decade at Langewens. Similarly, the magnitudes of decreasing winter river flow at Bree@Ceres and Berg@Franschoek are greater for the more recent 30-year period than for 1960–2017. Correlation coefficients for Vilij@Voeliv rainfall and four river flow stations Berg@Franschoek, Bree@Ceres, Wit River@Drosterkloof and Little Berg@Nieuwkloof) are stronger for shorter periods (i.e. 1987–2017 and 2007–2017) than that for the longer period, 1960–2017. The Intergovernmental Panel on Climate Change emphasises the importance of studies to assist with model prediction uncertainties. To this end, our study expands the understanding of regional hydrological responses to rainfall change in the water stressed region of the Western Cape Province.

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Vulnerability and impact of climate change on horticultural crop production in the Western Cape Province, South Africa

South African Journal of Botany ◽

10.1016/j.sajb.2007.02.142 ◽

2007 ◽

Vol 73 (2) ◽

pp. 321

Author(s):

S.J.E. Wand

Keyword(s):

Climate Change ◽

South Africa ◽

Crop Production ◽

Western Cape ◽

Western Cape Province ◽

Horticultural Crop ◽

Impact Of Climate Change

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Characterization of Rhizoctonia spp. Recovered from Crop Plants Used in Rotational Cropping Systems in the Western Cape Province of South Africa

Plant Disease ◽

10.1094/pd-90-1399 ◽

2006 ◽

Vol 90 (11) ◽

pp. 1399-1406 ◽

Cited By ~ 31

Author(s):

Y. T. Tewoldemedhin ◽

S. C. Lamprecht ◽

A. McLeod ◽

M. Mazzola

Keyword(s):

South Africa ◽

Crop Production ◽

Optimal Time ◽

Limiting Factor ◽

Western Cape ◽

Optimum Growth ◽

Western Cape Province ◽

Binucleate Rhizoctonia ◽

Weakly Virulent

Isolates of Rhizoctonia spp. associated with barley, canola, clover, lucerne, lupin, annual Medicago spp. (medic), and wheat were recovered during the conduct of a 4-year (2000 to 2003) crop rotation trial in the Western Cape province of South Africa. These isolates were characterized by determining their anastomosis group (AG), in vitro optimum growth temperature, and pathogenicity toward emerging and 14-day-old seedlings of all the aforementioned crops. During the 4-year rotational trial, 428 Rhizoctonia isolates, in all, were obtained. The most abundant multinucleate AG was AG-4 HG-II (69%), followed by AG-2-1 (19%), AG-3 (8%), AG-2-2 (2%), and AG-11 (2%). The population of binucleate Rhizoctonia spp. comprised AG-K (53%), AG-A (10%), AG-I (5%), and unidentified AGs (32%). The optimal time for isolating Rhizoctonia spp. was found to be at the flowering or seedpod stage (20 to 22 weeks after planting). Temperature studies showed that isolates belonging to AG-2-2, AG-4 HG-II, and AG-K had significantly higher optimum growth temperatures than those from other AGs. In pathogenicity assays conducted on emerging as well as 14-day-old seedlings, isolates of AG-2-2 and AG-4 HG-II were the most virulent on all crops. Rhizoctonia solani AG-2-1 was highly virulent on canola, moderately virulent on medic and lupin, weakly virulent on lucerne and barley, and nonpathogenic on wheat. AG-11 isolates were moderate to weakly virulent on all crops, with the exception of barley and wheat. AG-3 was weakly virulent on canola, lupin, and medic. AG-K was the only binucleate Rhizoctonia sp. capable of inciting disease in our assays. This is the first comprehensive study to elucidate the identity and potential importance of Rhizoctonia spp. as a yield limiting factor in crop production systems in the Western Cape province of South Africa.

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Drought: A Common Environmental Disaster

Atmosphere ◽

10.3390/atmos13010111 ◽

2022 ◽

Vol 13 (1) ◽

pp. 111

Author(s):

Israel R. Orimoloye ◽

Johanes A. Belle ◽

Yewande M. Orimoloye ◽

Adeyemi O. Olusola ◽

Olusola O. Ololade

Keyword(s):

South Africa ◽

Annual Rainfall ◽

Innovative Technology ◽

Western Cape ◽

Environmental Disaster ◽

Western Cape Province ◽

Climatic Zones ◽

Agricultural Industry ◽

Agriculture Sector ◽

Climate Fluctuation

Droughts have been identified as an environmental hazard by environmentalists, ecologists, hydrologists, meteorologists, geologists, and agricultural experts. Droughts are characterised by a decrease in precipitation over a lengthy period, such as a season or a year, and can occur in virtually all climatic zones, including both high and low rainfall locations. This study reviewed drought-related impacts on the environment and other components particularly, in South Africa. Several attempts have been made using innovative technology such as earth observation and climate information as recorded in studies. Findings show that the country is naturally water deficient, which adds to the climate fluctuation with the average annual rainfall in South Africa being far below the global average of 860 mm per year. Drought in South Africa’s Western Cape Province, for example, has resulted in employment losses in the province’s agriculture sector. According to the third quarterly labor force survey from 2017, the agricultural industry lost almost 25,000 jobs across the country. In the Western Cape province, about 20,000 of these were lost which has a direct impact on income generation. Many of these impacts were linked to drought events.

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