John Annandale

University of Pretoria | UP · Department of Plant and Soil Sciences

Response of wheat (Triticum aestivum L.) and cowpea (Vigna unguiculata L.) to foliar wetting with low pH mine waters containing acid-generating metal cations A B S T R A C T Acid mine drainage (AMD) contains metals that have detrimental effects on crop growth if present in excess in plant-available form. The use of untreated AMD from coal mines for...

Mine closure in the Witwatersrand Goldfields of South Africa has resulted in an acid mine drainage (AMD) legacy that is difficult to manage and costly to address. As a short-term measure, three large high-density sludge (HDS) plants were erected that treat 185 megalitres of AMD per day (ML/day), at great cost to taxpayers. Longer-term solutions are...

Irrigators are increasingly challenged to maintain or even increase production using less water, sometimes of poorer quality, and often from unconventional sources. This paper describes the main features of a newly developed software-based Decision Support System (DSS), with which the fitness for use (FFU) of water for irrigation (IrrigWQ) can be a...

Untreated acid mine drainage (AMD) is being considered for crop irrigation on strategically limed soils, but foliar scorching is of potential concern. To test whether crops might be protected by antitranspirants, a field trial and two glasshouse pot trials were undertaken during the 2020/2021 growing seasons. Crops, namely Sorghum bicolor, Zea mays...

Irrigators are increasingly challenged to maintain or even increase production using less water, sometimes of a poorer quality, and often from unconventional sources. This paper describes the main features of a newly developed software-based Decision Support System (DSS), with which to assess the Fitness for Use (FFU) of water for irrigation. Inclu...

Pearl millet is an important crop for food security in Asia and Africa’s arid and semi-arid regions. It is widely grown as a staple cereal grain for human consumption and livestock fodder. Mechanistic crop growth and water balance models are useful to forecast crop production and water use. However, very few studies have been devoted to the develop...

Due to population growth and agricultural intensification, water scarcity is increasing in the Upper Ewaso Ng’iro Basin. Quantitative information is needed to improve the management of this resource, but is a challenge due to lack of hydrometeorological data. Using water footprint thinking, a pragmatic approach applying available information and si...

Crop modelling has the potential to assist plant breeding by identifying favourable genotypic (G) traits for specific environments (Es). Sugarcane crop models have not been rigorously evaluated against a factorial GxE dataset. It is imperative that models are evaluated in this way before they are applied to plant breeding problems. Our objectives w...

Municipal sludge has economic value as a low-grade fertilizer as it consists of appreciable amounts of the macro and micronutrients. When using sludge as fertilizer, the economic aspect should be taken into account. In this study, the following specific objectives were identified: (a) to investigate the economic feasibility of using sludge as a fer...

Upland rice (Oryza sativa L.) production systems in sub-Saharan Africa are faced with challenges of water stress and nitrogen (N) deficiency, which reduce grain yield, water use efficiency (WUE), and nitrogen use efficiency (NUE). The objective of the study was to determine the response of upland rice to N fertilizer rates under well-watered condit...

Background: Very little has been researched about the efficacy, effectiveness, feasibility, sustainability and impact of food-based approaches on the diets and nutritional status of populations at risk of hunger and food insecurity. This study contributes knowledge about the impact of food-based approaches on the diets of populations at risk of hu...

Amidst conflicting narratives in development circles regarding the drive for nutrition-sensitive agriculture and the displacement of household production by supermarket penetration into deep rural areas, little is documented about the design of nutrition-sensitive agricultural programmes in the context of changing food systems. This is the first co...

Amidst conflicting narratives in development circles regarding the drive for nutrition-sensitive agriculture and the displacement of household production by supermarket penetration into deep rural areas, little is documented about the design of nutrition-sensitive agricultural programmes in the context of changing food systems. This is the first co...

Background Very little has been researched about the efficacy, effectiveness, feasibility, sustainability and impact of food-based approaches on the diets and nutritional status of populations at risk of hunger and food insecurity. This study contributes knowledge about the impact of food-based approaches on the diets of populations at risk of hung...

Management of nitrogen and water plays a significant role in increasing crop productivity. A large amount of nitrogen (N) may be lost through leaching if these resources are not well managed. Wetting front detectors (WFDs) and Chameleon soil water sensors were used to adapt water and nitrogen applications with the goal of increasing millet yields,...

Crop improvement aims to produce high yielding genotypes for target environments. Crop models simulate yield formation as the outcome of a series of low-level processes, driven by environmental (E) variables and regulated by genetic (G) traits. There is potential for crop models to aid sugarcane breeding, by identifying desirable genetic traits for...

When applying municipal sludge according to crop N requirements, the primary aim should be optimizing sludge application rates in order to maximize crop yield and minimize environmental impacts through nitrate leaching. Nitrate leaching and subsequent groundwater contamination is potentially one of the most important factors limiting the long-term...

Orange-fleshed sweet potato (OFSP) leaves can be utilised as a fresh green leafy vegetable, in addition to the traditional use of storage root; therefore, OFSP can be seen as a "dual-purpose'' crop. We hypothesized that no vine harvesting combined with fertiliser application and irrigation will improve the storage root yield and selected plant para...

Traditional vegetables are piloted as champion species for sub-Saharan Africa, a region experiencing high levels of nutritional food insecurity and water scarcity. The important benefits of traditional vegetables over alien vegetables are; (i) their high nutrient density (iron, zinc, and β-carotene), (ii) their productivity under water stress, and...

The application of water footprint accounting is mostly done at large scales, but the estimation of crop- and region-specific water footprints for up-scaling is dependent on accurate and representative in-field measurements of evapotranspiration (ET), yield and irrigation. In a field trial we assessed the influence of maize (Zea mays L.) ET estimat...

Classification of waste is an essential part of waste management to limit potential environmental pollution; however, global systems vary. The objective was to understand the waste classification of high density sludge (HDS) from acid mine drainage (AMD) treatment, according to selected global systems. Three sludges from two limestone treatment pla...

High-value vegetable crops are typically grown under irrigation to reduce production risk. For water resource planning it is essential to be able to accurately estimate water use of irrigated crops under a wide range of climatic conditions. Crop water use models provide a means to make water use and yield estimates, but need crop- and even cultivar...

Food production in water-scarce countries like South Africa will become more challenging in the future because of the growing population and intensifying water shortages. Reducing food wastage is one way of addressing this challenge. The wastage of carrots, cabbage, beetroot, broccoli and lettuce, produced on the Steenkoppies Aquifer in Gauteng, So...

Rice (Oryza sativa L.) grown in uplands is exposed to variable soil water conditions and unpredictable periods of water stress (WS). The study was conducted to determine the impacts of WS imposed at different phenological stages of upland rice on growth, phenology, recovery of source size, yield and water use efficiency (WUE). The popular cv. Neric...

Future water scarcities in the face of an increasing population, climate change and the unsustainable use of aquifers will present major challenges to global food production. The ability of water footprints (WFs) to inform water resource management at catchment-scale was investigated on the Steenkoppies Aquifer, South Africa. Yields based on croppi...

Background: There are concerns that fertilization using sludge in semi-arid areas, where water is limiting, will compound the effect of drought, resulting in the decline of yield from potential salt accumulation. We investigated (8 years) impacts of annual sludge application at 0, 4, 8, and 16 Mg ha(-1) on weeping love grass hay yield, crude prote...

Subtropical fruit crops form an important part of the fruit industry in many countries. Many of these crops are grown in semi-arid regions or subtropical regions where rainfall is seasonal and as a result the vast majority of these perennial, evergreen orchards are under irrigation. This represents a significant irrigation requirement and with more...

The accurate estimation of evapotranspiration (ET) of orchard crops is critical for judicious irrigation water management and planning. However, it is impossible to measure ET under all possible combinations of climate and management practices, which necessitates the use of ET models. Although empirical models are more likely to be adopted by consu...

Food production comes at an ecological cost, and the lack of sustainability of South Africa’s crop production systems is becoming increasingly worrisome. While small scale emerging and homestead subsistence farming are significant in the agricultural sector, food production is dominated by large scale commercial agriculture. In this paper we analys...

Irrigation Guidelines for Mixed Pastures and Lucerne

Irrigated agriculture is facing fierce competition for a substantial share of water as the water demand for industrial, domestic, municipal and other activities are increasing rapidly. The increasing shortage of irrigation water in addition to the increasing cost of fertiliser creates a great need to improve the practices of irrigation through bett...

Water footprint (WF) accounting as proposed by the Water Footprint Network (WFN) can potentially provide important information for water resource management, especially in water scarce countries relying on irrigation to help meet their food requirements. However, calculating accurate WFs of short-season vegetable crops such as carrots, cabbage, bee...

The potential of tree arrangement in optimizing radiation and soil water distribution and crop yield of hedgerow intercropping systems was investigated using a Jatropha curcas–Pennisetum clandestinum (kikuyu) system (Ukulinga, South Africa). Treatments (1110 t ha−1) of Jatropha-only (JO), single-row Jatropha and kikuyu (SR), and double-row Jatropha...

Soil organic matter (SOM) is tightly linked to soil quality, but cultivation generally causes a decline in SOM, reducing soil quality and releasing carbon dioxide into the atmosphere. Internationally, countries are expected to reduce their greenhouse gas (GHG) emissions, and compile and update GHG inventories. Many developing countries, such as tho...

The expected rate of nitrogen (N) mineralisation is key to sludge recommendation rates for agricultural lands. The presence of a combination of factors (biotic and abiotic) that contribute to the variation in N release at different sites is the main obstacle to sludge application rate recommendations. Nonetheless, the use of a single annual N miner...

This second edition, which includes 12 chapters, provides an important update on tree-crop interactions over the last two decades. Three new chapters have been added to describe the new advances in the relationship between climate change adaptation, rural development and how trees and agroforestry will contribute to a likely reduction in vulnerabil...

Water and nitrogen shortages in annual ryegrass (Lolium multiflorum) production can be improved by using proper irrigation and nitrogen scheduling methods. The aim of this research was to analyse the effect of water and nitrogen application on dry matter production and forage quality of annual ryegrass. Treatments consisted of three irrigation leve...

Process-based computer simulation models are often used as reasoning support tools to integrate the complex processes involved in the soil-plant-atmosphere system. The objectives of this study were to evaluate the performance of the SWB-Sci model as a reasoning support tool for sludge management in agricultural lands, and use the validated model to...

Sludge application to agricultural lands is often limited mainly because of concerns about metal accumulation in soils and uptake by crops. The objective of the study was to test the following hypotheses: (i) in the short to medium term (5–10yr), the application of good-quality sludge according to crop N requirements will not lead to significant ac...

Agriculture, as the largest user of fresh water worldwide, is under close scrutiny to justify its use of water due to the increase in competition from a number of end-users. Apart from on-farm measures to increase water use efficiency, government intervenes through policy instruments to influence water use behaviour. Citrus growers need to take hee...

The estimation of crop water use is critical for accurate irrigation scheduling and water licenses. However, the direct measurement of crop water use is too expensive and time-consuming to be performed under all possible conditions, which necessitates the use of water use models. The FAO-56 procedure is a simple, convenient and reproducible method,...

The quantification of water use of citrus orchards is important in order to prevent stress developing in the orchard and to avoid wasting precious water resources. Measurement of citrus orchard water use is not possible under all environmental and management combinations because of the expense and time it takes to make the measurements. Models whic...

Protecting the environment from contaminated mine water decanting in increasing volumes from the goldfields presents an enormous challenge, probably greater than that of coal mine water because the decant points are in urban areas. Some of the water is acidic but most of it is partly neutralised through water-rock interaction. The main limitation o...

Poor irrigation management in pastures can lead to yield and quality reduction as well as loss of income through extra pumping and leaching of nitrate fertiliser. A number of irrigation scheduling techniques of varying levels of sophistication have been developed over the years to address limited irrigation water availability and maximise productiv...

The terms of reference for this project required the measurement of the unstressed water use and ancillary variables of at least 4 types of fruit tree/orchard crops at selected sites to enable modeling using available South African or international models. Furthermore, the conditions stipulated that the selection should be representative of sub-tro...

Heat pulse velocity sap flow measurement techniques are considered reliable and accurate for estimating tree water use in woody species. In order to be representative and scalable, probes are typically installed in a number of sample trees and inserted to stratified depths to account for heterogeneity in hydraulic conductivity exhibited by the sapw...

Karst aquifers in dolomites are the single most important type of aquifer in South Africa. One such aquifer is the Steenkoppies Aquifer, situated west of Tarlton (26°02′–26°13′ S, 27°29′–27°39′ E), which covers an area of 213 km2 with a catchment area of 311 km2. A perennial spring, Maloney’s Eye that discharges into the Magalies River, serves as t...

Land application of sludge has been shown to improve soil properties and aid crop growth, but the possibility of constituent nutrients such as nitrogen and phosphorus reaching environmentally toxic levels has caused governing authorities to set limits to how much sludge can be applied to agronomic land. The high nitrogen utilisation potential of pa...

Low yields of East African highland bananas (Musa spp. AAA-EA) are often attributed to poor and declining soil fertility, which outweighs other biophysical factors and management practices. We investigated the influence of planting density on nutrient mass fractions and nutrient imbalance indices in bananas under small-scale, low-input systems usin...

Rehabilitating coal gasification ash dumps by amendment with waste-activated sludge has been shown to improve the physical and chemical properties of ash and to facilitate the establishment of vegetation. However, mineralization of organic N from sludge in such an alkaline and saline medium and the effect that ash weathering has on the process are...

The determination of accurate figures for orchard water use is critical for improved irrigation scheduling and for the issuing of water licenses. Under- or overestimations can have serious implications for production and water resources in water scarce countries, such as South Africa. In order to meet this need for more definite water use figures t...