Mapping soil organic carbon at a terrain unit resolution across South Africa

Geoderma ◽  
2020 ◽  
Vol 373 ◽  
pp. 114447
Author(s):  
Roland E. Schulze ◽  
Stefanie Schütte
Keyword(s):  
South Africa ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Terrain Unit ◽  
Unit Resolution

scholarly journals Soil Organic Carbon and Labile Carbon Pools Attributed by Tillage, Crop Residue and Crop Rotation Management in Sweet Sorghum Cropping System

2020 ◽  
Vol 12 (22) ◽  
pp. 9782
Author(s):  
Mashapa Elvis Malobane ◽  
Adornis Dakarai Nciizah ◽  
Fhatuwani Nixwell Mudau ◽  
Isaiah Iguna Chabaari Wakindiki
Keyword(s):  
South Africa ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Quality ◽  
Sweet Sorghum ◽  
Crop Residue ◽  
Cropping System ◽  
Water Extractable Organic Carbon ◽  
Water Extractable ◽  
Residue Retention

Labile organic carbon (LOC) fractions are considered as sensitive indicators of change in soil quality and can serve as proxies for soil organic carbon (SOC). Although the impact of tillage, crop rotation and crop residue management on soil quality is well known, less is known about LOC and SOC dynamics in the sweet sorghum production systems in South Africa. This short-term study tested two tillage levels: no-till and conventional-tillage, two crop rotations: sweet-sorghum/winter grazing vetch/sweet sorghum and sweet-sorghum/winter fallow/sweet sorghum rotations and three crop residue retention levels: 30%, 15% and 0%. Tillage was the main factor to influence SOC and LOC fractions under the sweet sorghum cropping system in South Africa. NT increased SOC and all LOC fractions compared to CT, which concurs with previous findings. Cold water extractable organic carbon (CWEOC) and hot water extractable organic carbon (HWEOC) were found to be more sensitive to tillage and strongly positively correlated to SOC. An increase in residue retention led to an increase in microbial biomass carbon (MBC). This study concludes that CWEOC and HWEOC can serve as sensitive early indicators of change in soil quality and are an ideal proxy for SOC in the sweet-sorghum cropping system in South Africa.

scholarly journals Soil fertility constraints and yield gaps of irrigation wheat in South Africa

2017 ◽  
Vol Volume 113 (Number 1/2) ◽  
Author(s):  
Nondumiso Z. Sosibo ◽  
Pardon Muchaonyerwa ◽  
Lientjie Visser ◽  
Annelie Barnard ◽  
Ernest Dube ◽  
...  
Keyword(s):  
South Africa ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Conservation Tillage ◽  
Phosphorus Deficiency ◽  
Conservation Agriculture ◽  
Geographical Regions ◽  
Kwazulu Natal ◽  
Yield Gaps ◽  
Irrigated Wheat

Abstract South Africa currently faces a wheat (Triticum aestivum L.) crisis as production has declined significantly over the past few years. The objective of this study was to explore opportunities for improving yields in intensive irrigated wheat production systems of South Africa through analyses of yield gaps, soil fertility constraints and conservation agriculture practices. The study was conducted in the major irrigation wheat production areas across four geographical regions: KwaZulu-Natal, eastern Highveld, warmer northern and cooler central. Actual yield (Ya) based on long-term yield data ranged from 5.99±0.15 t/ha to 8.32±0.10 t/ha across different geographical regions. The yield potential (Yp) ranged from 7.57 t/ha to 11.45 t/ha. Yield gaps (Yp–Ya) were in the range of 1.58–3.13 t/ha. Yields could be increased by 26–38% through closing yield gaps. On 88.37% and 13.89% of the fields in the KwaZulu-Natal and warmer northern regions, respectively, there was strong evidence of the practise of conservation agriculture, but none in the other regions. On 42.31% of irrigated wheat fields, soil organic carbon was below 1% at a soil depth of 0–20 cm. Fields in which conservation tillage was practised had double the soil organic carbon of conventionally tilled fields (2.15±0.10% versus 1.02±0.05%), but greater acidity and phosphorus deficiency problems. Sustainable approaches for addressing phosphorus deficiency and acidity under conservation tillage practices need to be sought, especially in the KwaZulu-Natal region.

scholarly journals Macadamia Husk Compost Improved Physical and Chemical Properties of a Sandy Loam Soil

2021 ◽  
Vol 13 (13) ◽  
pp. 6997
Author(s):  
Dembe Maselesele ◽  
John B.O. Ogola ◽  
Romeo N. Murovhi
Keyword(s):  
South Africa ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Bulk Density ◽  
Soil Ph ◽  
Sandy Loam ◽  
Inorganic Fertilizer ◽  
Total N ◽  
Loam Soil ◽  
Water Holding

Poor soil fertility caused mainly by low and declining soil organic carbon is one of the major constraints limiting crop productivity in tropical and subtropical regions of South Africa. We evaluated the effect of macadamia husk compost (MHC) on selected chemical and physical properties of a sandy loam soil in NE South Africa in two successive seasons. The treatments, laid out in randomised, complete block design and replicated four times, were: (i) zero control, (ii) inorganic fertilizer (100:60:60 NPK Kg ha−1), (iii) MHC at 15 t ha−1, and (iv) MHC at 30 t ha−1. Soil bulk density; water holding capacity; soil pH; electrical conductivity (EC); organic carbon; total N; and available P, K, Ca, Mg, Al, Zn, and Cu were determined at 0–15 cm soil depth. Macadamia husk compost application decreased bulk density and increased water holding capacity. MHC and inorganic fertilizer increased soil pH, organic carbon, total N, C:N ratio, available P, exchangeable cations, and micronutrients but the effect was more pronounced under MHC treatments in both seasons. The positive effect of MHC on soil physicochemical properties was associated with an increase in soil organic carbon due to MHC application; hence, MHC may offer a sustainable option of increasing soil productivity, particularly in areas characterised by low SOC.

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