Every presentation ended with the sentiment that research was vital to success in agriculture. This echoed what Prof Linda du Plessis, vice-principal of North West University, had said: “We might rely on a doctor once a year, a lawyer once a year, but we rely on a farmer for three meals a day.”
The Unit for Environmental Sciences and Management aims towards holistically instilling a culture of research development into its students, who as farmers in the future will bear great responsibility.
Any individual or organisation that serves agriculture should understand that research plays a vital role in the development and enhancement of agriculture, food security, environmental sustainability, economic development, and the well-being of rural and urban populations. This ethos was evident in the final-year students’ presentations.
As part of their syllabus, all BSC Agriculture students are required to conduct agricultural research projects during their final year. Their research questions, findings, methodology and implications were presented to the entire departmental academic board, peers, and guest evaluators from the Department of Agriculture and Rural Development and the Agricultural Research Council.
Most impressive was the overall understanding among these future farmers of the vital role that training and research played in navigating challenges in a rapidly growing economy. Each presentation explored highly current and topical challenges faced by the agriculture sector.
The projects addressed increased food production, food security, sustainability, crop disease management, biodiversity, technological advancements, economic growth, climate change mitigation and adaption.
A total of 16 group research projects were presented. Read the extracts below:
Allelopathic potential of Amaranthus Palmeri on maize seed germination and early root development by CJH Kruger and C Muller
Unit for Environmental Sciences and Management, North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa
Amaranthus palmeri stands out as a highly competitive weed species, recognized for causing substantial yield losses in crops like maize, cotton, and soybean in the USA and globally. Recently, Amaranthus palmeri was detected in South Africa, prompting the need to investigate its least reported impact on crops, i.e., its allelopathic effect. Literature exists for its allelopathic effect on crop species with little to no reports on gender differences with regards to allelopathic potency of A. palmeri. This study sought to explore the allelopathic potential and differences in potency of male and female A. palmeri plants by employing the bioassay technique for testing effects of aqueous leaf extracts at various concentrations (Treatments 1-10) on the germination of maize seeds and radicle (primary root) growth in petri dishes in a sterile laboratory. Additionally, the coleoptile length of male and female seedlings was measured. A substantial impact on root growth and vigour was observed, with increasing concentrations of leaf extracts significantly inhibiting the growth and development of radicles. In one treatment male plants tended to have a positive influence on germination and the early stages of root growth. Results confirm that the water-soluble allelochemicals present in A. palmeri leaf material exert an inhibitory allelopathic influence on maize seeds, with female plants demonstrating more pronounced allelopathic effects than male plants overall. T tests comparing the male and female plants indicated varying differences in potency at different concentrations between the two plants with p-values ranging from 0.0390 and 0.9921 (alpha = 0.05).
Developing a nitrogen fertility management program for pot-raised wheat crop by HB Keyser, MP Bezuidenhout and D Gunther
Pot experiments provided better control over environmental variables compared to field experiments. However, they lacked a nitrogen (N) management program. This study aimed to develop an effective N management program for pot-raised wheat crops. The experiment employed a factorial design with N estimation methods (Furrow slice – F, Area – A, Population – P), N application rates (N1, N2), and timing (Once-off – O, Three-splits – T) as primary factors. N quantities applied per pot were calculated based on plant population, pot surface area, and furrow slice. These derived N quantities were either applied as is or doubled to create two application rates. Two application timings, single (O) and split (T, 3 times), were implemented. The study consisted of 12 treatments replicated four times, totalling 48 pots. Key findings highlighted that treatment “FN2T” consistently exhibited high chlorophyll content, signifying robust photosynthesis and efficient nutrient utilization. In contrast, “AN20” excelled in root mass development, essential for nutrient absorption and plant stability. Furthermore, “FN2T” demonstrated superior above-soil biomass, crucial for comprehensive plant growth. Regarding wheat ear weight, both “AN2T” and “FN2T” treatments outperformed others, emphasizing their potential to enhance wheat yield. These findings offer valuable insights into optimizing agricultural practices for increased wheat productivity and quality, underscoring the significance of tailored treatments in wheat cultivation.
The effect of molasses and sojamax on agronomic and physiological traits of soybean and cowpea by H Bester, JG Jones, D Opperman and NZ Ngobese
Soybean and cowpea hold great potential as permanent, rotation or cover crops for commercial farmers in South Africa. However, land degradation associated with unsustainable nutrient management practices compromise this potential. This study evaluated how selected organic (molasses) and inorganic (sojamax) fertilizer products influence the agronomic and physiological traits of both crops to develop improved cultivation protocols. Cowpea and soybean seeds were sown in 20 L pots in a controlled environment in winter. The experiment was arranged in a completely randomized design with seven replicates. Sojamax and molasses (LS33) were applied as foliar spray treatments, at concentrations of 1.3% and 1.2%, respectively, at a plant height of 10-15 cm. The treatments were compared to a control (Yara [6:2:1]) foliar spray applied after emergence. Plant height, number of leaves, leaf length, leaf width and leaf chlorophyll concentration were assessed at various stages during plant development. Results show that chlorophyll content significantly differed among the treatments in the molasses for both crops (p-value <.001). However, plant height, number of leaves, leaf width and leaf length are non-significantly different. The results show that molasses increased the leaf chlorophyll concentration of cowpea (49.67), when compared to the control (46.22), whilst differences in soybean are non-significant. This study suggests that treatments have no influences on the agronomic and physiological traits of both crops. However, further research is required to test for significance. This experiment could be repeated under favourable conditions and allowed to run to the end of the season to get indications of yield.
Investigating the phenology of maize tillers under different nitrogen rates and related effects on maize growth and development by JA van Heerden, R Nel and R Smalberger
Maize is one of the most important crops planted every year in South Africa. In many cases, maize plants produce tillers which have been believed to have a negative impact on plant growth and grain yield. In this study, we used recently introduced maize varieties. We tested the impact of N application rate and tiller management on crop growth and grain yield. The study had a total of 4 recently released maize varieties, two N application rates targeting 6 and 12 t/ha grain yield, and two tiller management of removal and non-removal. The experiment was replicated three times to give a total of 48 pots. The trial was carried out in a tunnel in Potchefstroom in the North-West province, South Africa. The study closely monitored several physiological, morphological and yield parameters (germination percentage, plant height, Brix̊ reading, chlorophyll content, leaf area, and grain yield) to measure the impact of variety, tiller management and N rate on crop growth and yield. The findings of the study will provide relevant information on improving the efficiency of maize production. To our surprize the results showed that different N rates did not necessarily have an impact in development of tillers but significantly influenced different aspects of the experiment such as plant height, chlorophyll content ext. at different sampling dates.
Cultivar, planting date and nitrogen rate effects on Sclerotinia sclerotiorum of sunflower by M Cloete, PW Jansen and K Schemel
Sclerotinia sclerotiorum can lead to yield losses of up to 80 % in sunflower production and is difficult to control due to a host range of more than 500 host plants. Current information regarding sunflower cultivars with a degree of resistance is lacking. The aims of this study is therefore to screen commercially available cultivars in the North-West area for resistance and to determine the effect of planting date and nitrogen rates on disease development in two separate field trials. Data from 11 common cultivars screened over a three-year period (2020/21 – 2022/23) in Potchefstroom was analysed to determine cultivar reactions against S. sclerotiorum infections. Cultivars SY3970Cl, AGSUN5103, AGSUN5106, AGSUN5108 showed resistance and cultivars P65LP54, P65LP65 and AGUARA6 were susceptible. In the second field trial with nitrogen rates ranging from 0 (control) to 120 kg/ha, the 0 (control) application had significantly highest S. sclerotiorum infection (0.54 cm2) and the 90 and 120 kg/ha applications had significantly lowest S. sclerotiorum infection (0.32 and 0.35 cm2). Five cultivars were included in this field trial and AGSUN8251 exhibited the lowest mean development of S. sclerotiorum disease, while cultivar PAN7158HO displayed the highest mean disease development. ANOVA results showed that the first planting date yielded significantly larger mean S. sclerotiorum lesion sizes (0.48 cm2) compared to the second planting date (0.38 cm2). With this study we could identify cultivars with sources of resistance which can aid farmers and seed companies to make informed management decisions. Nitrogen deficiency can increase disease and planting date can be used to avoid infections at critical growth stages.
Validating an ecological toolset for soil ecosystem health and functioning agricultural systems by BF Wessels, C van Wyk and D Axsel
A healthy soil can support ecosystem functioning (e.g., nutrient cycling and carbon regulation), which plays an important role in agricultural productivity and sustainability. Soil health is generally measured using assessment frameworks (e.g., Soil Health Tool) that are often laborious and expensive, also requiring specialized equipment. Therefore, we aimed to validate nematode community structure as an ecological toolset capable of complementing the biological component of soil health assessments. Physicochemical indicators of soil fertility and structure were also included to support the interpretation of ecological data and furthermore to see if nematode community structures can be used as a single indicator of soil health. For this study, soil samples were collected from six different ecotopes each consisting of three management treatments, namely, conventional tillage, regenerative agriculture and no-till. The mean levels for the different nematode indices were visualized in clustered bar graphs as well as ANOVA tests to see if there were any statistical differences between the ecotopes and management strategies. Soil health scores from the different trials and treatments were compared using correlation, regression, and analysis of variance tests. The clustered bar graphs indicate moderately strong correlation between the ecotopes, as well as the ecotope-system interactions with the Maturity Index. The linear regression graphs show that there is a positive correlation between the percentage of sand and the PP4 nematode group. This study shows that different nematode structures and how they correlate with certain physical and chemical parameters can be used to determine soil health.
Characterising major weather and climate-related disruptions in the maize triangle and their associated synoptic patterns using machine learning by S Lourens, RF Pretorius and C Rossouw
Recent years have seen major crop losses in South Africa’s maize triangle as a result of extreme weather conditions. Concern has been raised due to the significant impact these disruptions have had on maize production. To better understand how these extreme weather events develop, this study tries to recognize and classify them together with the synoptic patterns that they are connected with. The objective is to make it possible for future risk reduction and improved preparedness actions. Historical weather data spanning the past 50 years, provided by Caelum, was analysed. The results showed that the most extreme weather conditions that had an impact on maize production were most common in the summer and were frequently associated with catastrophic precipitation occurrences. Further investigation identified the main contributors to major damage as convective weather events, such as hailstorms, floods, and tornadoes. The metrics Geopotential at 500hPa, Convective Available Potential Energy (CAPE), and Mean Sea Level Pressure (MSLP) were used to determine the typical synoptic patterns connected to these events after they were manually identified. The Machine learning technique, Principal Component Analysis (PCA) was employed to characterize each event type and its corresponding synoptic patterns. The research showed that most of these patterns were associated with ridging high-pressure systems and Tropical Temperate Troughs (TTT). Understanding these weather system tendencies can help reduce future hazards to South Africa’s maize output. This thorough method offers useful information and techniques for mitigating the effects of extreme weather events on the region’s maize farming.
Photosynthesis responses of maize (Zea mays ) to glyphosate by KAY Bogatsu, K Motale and M Ramolai
Little is known about the effect of glyphosate on the physiological attributes of maize varieties, specifically chlorophyll biosynthesis. Pots were arranged in a polyethylene-tunnel facility at Ecorehab according to a completely randomized block design to determine the effect of glyphosate on the photosynthetic performance of two maize varieties; IMP-53 is glyphosate-resistant, and Zama Star is glyphosate-susceptible. Glyphosate was applied to the maize plants at the V2 growth stage at different dosages (0.002 mL/m2, 0.001 mL/m2, 0.004 mL/m2). The parameters used to evaluate the photosynthetic performances were PI ABS (photosynthetic performance index), Dlo/RC (energy lost in the form of heat dissipation per reaction center), RC/abs (density of active reaction centers, like chlorophyll content measurements), PI total (photosynthetic performance index) and FV/FM (structural integrity of photosystem II) using a handy-PEA chlorophyll fluorimeter. The ANOVA analysis revealed that there are significant differences in FV/FM, /RC, RC/abs, and PI ABS at 24-hour duration after glyphosate application and FV/FM, Dlo/RC, RC/abs, and PI ABS at 96-hour duration after glyphosate application on both the treatments (R1, R2, R3, and C) due to the different dosages and type of maize variety. The maize varieties showed significant differences in FV/FM, which showed a progressive decline, indicating that photosynthesis II functions are not responding because of plant stress due to glyphosate application. The application of glyphosate at different dosages in Zama Star was more severe since it is glyphosate susceptible.
The effect of SmartBlock, a sprout suppressant, on the physiological growth of potato (Solanum tuberosum) by JK Mashishi, SD Motene and NZ Ngobese
SmartBlock® is a newly introduced sprout suppressant proposed as an alternative to Chlorpropham (CIPC) for increasing the shelf-life of potatoes in packhouses. While studies show SmartBlock is effective, its effects on the regeneration of seed are unknown. The present study investigates the effects of SmartBlock on the physiological growth of Mnandi and Vanderplank seed in a pot experiment. Seed potatoes pretreated with two dosages (0.100 µL/kg and 0.135 µL/kg) of SmartBlock were planted in a controlled environment and compared to a control (no sprout suppressant). Data on the emergence rate, plant height, number and diameter of stems, leaf area, chlorophyll content, transpiration, stomatal conductance, and CO2 assimilation were collected and analysed with Genstat. The results show that SmartBlock slowed the emergence in both cultivars. The control reached 100% emergence in 13 days whereas the 0.100 µL/kg treatment reached 100% emergence 15-19 days after planting (DAP). Only 80% of the potatoes treated with 0.135 µL/kg SmartBlock emerged and this was reached at 21 and 17 DAP, respectively. Statistical analysis revealed the two SmartBlock treatments decreased CO2 assimilation and stomatal conductance (p=0.029 and p<0.001, respectively), which are key indicators of the net photosynthetic rate in plants. However, plant height, number and diameter of stems, leaf area, chlorophyll content and transpiration non-significantly differed (p>0.05). Since photosynthesis is linked to tuber development, the findings of this study suggest SmartBlock could negatively affect the yield of potatoes. Further studies are recommended to evaluate the influence of the sprout suppressant on yield components.
Using digital soil mapping methods for precision agriculture by J Geraldes, G Nieuwoudt and MS Lehana
The agricultural industry is pressured to yield more produce, as a result of increasing world population. Precision agriculture (PA) can contribute to solving this issue as its implementation can lead to increased yields. However, PA requires the use of soil mapping to enable decisions to be made for variable rate application. Currently, conventional soil mapping methods require data that is acquired from a high number of soil samples at a high cost. Digital soil mapping (DSM) has been shown to produce accurate soil property maps at regional scales, using machine learning and environmental covariates. The hypothesis tested in this study is that using DSM methods, soil property maps commonly used for PA can be created using significantly less soil samples, thus lowering the cost, but at an equal or better accuracy than conventional methods. To test the hypothesis soil property maps were created using conventional interpolation on a 1 ha grid, as well as DSM methods using only 50% and 25% of the available data points. The two types of maps were visually and statistically compared with one another. The covariates tested were calcium content, magnesium content, potassium content, sodium content, carbon content, pH, phosphorus content as well as the sand, silt and clay percentages. The semivariograms of the covariates show that the 100 metre grid sizes are too big to be accurate over distance and interpolate accurately, with the exception of phosphorus, which has a range of over 100 metres (approximately 150 metres). For all of the covariates, except phosphorus, Kriging is not scientifically sound. Machine learning algorithms should rather be utilised as they can deliver more accurate results with less samples needed. The use of machine learning algorithms resulted in the same accuracy as the Kriging method, however, it utilised less data points than what the Kriging method needed.
Assessing the weather and climate forecasting needs of grain farmers in the Western maize triangle by JJ van Rooyen, J van Zyl and BD Minnaar
The grain sector is important in South Africa for food security and the economy. Providing the agricultural sector with accurate weather forecasts will ensure a successful and more stable grain production nationally. Technology has made it possible to create specific weather forecasts just for the grain sector. This study will examine farmers’ current use of weather and climate services, we will be evaluating the data collected from farmers by means of surveys and questionnaires. It will provide essential information to the grain sector by addressing the weather and climate needs of current farming practices. It will provide the farmers as well as private weather institutions with the necessary insight to address the challenges they face daily, monthly as well as seasonally. In return the adaptations to the current weather situation will provide a stronger grain sector that will be able to withstand challenges regarding food security and a declining economy. In this study, we found that only 18,2% of the participants uses specialised agricultural weather forecasting products, although, we found that more farmers are interested in the use or adaption to more accurate and advanced products in their farming practises. Of all the participants in the study, only 1,5% reckons premium weather forecasting products to be too expensive, however, 40,1% only uses freely available products. By utilising this information, the adaptations to the current weather situation will provide a stronger grain sector that will be able to withstand challenges regarding food security and changing climate
Role of winter cover crops in phosphorus cycling by R Champion and N Davel
Winter cover crops are essential for sustainable agriculture, reducing erosion, enhancing soil organic matter, and promoting biological activity in soils. This study examined the effect of different winter cover crop species on phosphorus cycling in two soil types. A greenhouse pot experiment with 14 treatments (seven cover crops x two soils) was conducted using a highly fertile soil (45.7 mg kg-1 ) from Agricol and a low-fertility soil (1.0 mg kg-1) from JJ Sand. Cover crops included: winter rye, winter wheat , winter barley, common vetch, white oats, cover crop mix (a mixture of the cover crops above) plus a no-crop control treatment. Treatments were arranged in a randomised complete block design and replicated three times. Soils used were analysed for total P and plant available P concentrations prior to planting. The ability of different cover crops to mobilize unavailable P and increase its availability differed significantly (P<0.05). In the Agricol soil, white oats resulted in the highest increase (12.3%) in available P concentrations while winter rye significantly lowered the initial P concentration by 4.8% (43,5 mg kg-1 P).In the JJ sand soil, all cover crops resulted in an overall increase of available P, however the increase in common vetch treatment was the lowest (3,4 mg kg-1 P) while in the winter wheat treatment the increase was the highest (7,16 mg kg-1 P).We recommend using white oats and winter wheat as a cover crops in fertile (high P) and low-fertility (low P) soils, respectively.
Evaluating the ecological maturation of the Johnson Su composting process by D de Lange, JA Visser and RM Strydom
The Johnson Su composting process involves the mixing of various organic materials, and the key question is when and how compost matures. Maturity can be influenced by temperature, moisture levels, and oxygen content within the compost. The purpose of this research is to determine whether compost maturity in the Johnson Su composting process can be determined by studying nematode communities. The research was conducted by building six bioreactors comprising a mixture of 10% horse manure, 20% woodchips, and 70% dried grass. To maintain appropriate moisture levels, the compost was irrigated daily. Once a month, compost samples were collected and nematodes extracted using the sugar centrifugal flotation method. Nematodes were counted and identified to genus or family level. During six months of compost maturation, the nematode community structure changed with a rise in the proportion of omnivorous nematodes. In addition, large fluctuations in populations of bacterivore, fungivore and predatory nematodes were observed across time. Significant changes in moisture levels and the carbon-to-nitrogen (C:N) ratio were also recorded, indicating continuous decomposition of the organic materials. Although variations in pH values and the nematode maturity index were observed, they were not statistically significant. Therefore, even though noticeable changes can be used as markers of the maturation process, more investigation is required before these changes can be used as the benchmark for determining compost maturity in the Johnson Su composting method.
Impact of hydraulic properties and other characteristics of soils on plant available water scheduling for maize and pecan nuts by Charl Strydom and Sep Uys
It is estimated that approximately 1.5 million hectares of crops are cultivated under irrigation in South Africa. Soil available water capacity plays a big role in ensuring the sustained fulfilment of crop water demand throughout various growth stages of irrigated crops. In a water-scarce agricultural landscape like South Africa, the implementation of pertinent irrigation scheduling criteria is imperative to secure plant-accessible water for optimal growth. The objective of this study was to analyze soils for hydraulic properties and other characteristics that influence the scheduling of irrigation on maize and pecan nuts. The study makes recommendations for the irrigation of these two crops.
The study was conducted at Agricol Trial Farm in the Potchefstroom area, where maize is cultivated under a linear moving irrigation system and pecan nuts with a micro-sprinkler irrigation system. Key soil hydraulic properties analyzed were field capacity, permanent wilting point, available water capacity, infiltration rate as well as fundamental attributes of texture, pH, and electrical conductivity. These analysis metrics formed the foundation for developing an irrigation model for water requirements of each of the two crops. Consequently, this model forms the basis for irrigation schedules that eliminates water stress and promotes optimal growth. Furthermore, the employed irrigation model scenarios will offer valuable insights and practical recommendations for the farm’s irrigation methodology. This comprehensive approach aims to enhance crop productivity by optimizing the water use efficiency of the produced crops and supporting the sustainable utilisation of a critical resource in South Africa.
Creating a hydraulic pedotransfer function for South African soils by A Jacobs, V Cooke and EC Verwey
Accurate soil measurements are key to feeding an increasing population with limited resources. By eliminating the need for time-consuming and expensive laboratory tests, pedotransfer functions (PTFs) present a promising way to speed up soil property evaluations. The study aim was to create pedotransfer functions (HPTFs) to predict hydraulic conductivity (K-Sat) in soil using easily measurable soil properties. 214 soil cores have been collected from five different catchments from which the soil properties were analyzed with the focus on, K-sat, carbon, texture, and structure, along with undisturbed samples to calculate the saturated hydraulic conductivity and bulk density in the lab. The machine learning algorithm Cubist was used to develop the PTFs for each catchment and one national pedotransfer function. The accuracy of the PTFs was determined with an independent set of soil data, regional PTFs proved more accurate than the national PTF. The values recorded showed that Tsitsa produced the most accurate model with a mean absolute error of 13.16 and a root mean square error of 14.06. This is admissible and means that pedotransfer functions can predict hydraulic conductivity to an acceptable level when using a quality dataset. However, when the PTF’s for Tsitsa are applied to another catchment it won’t yield aceptable results for accurate predictions. Thus, each PTF must be tailored to a specific area with similar properties across the board.
Phosphorus use efficiency of commonly grown potato cultivars in South Africa by JC Compion, JJ Zwiegers and H Oosthuizen
Phosphorus is an essential macronutrient required for various biochemical processes in potato (Solanum tuberosum) production. However, its limited availability in the soil due to fixation and low solubility often makes it the limiting factor. Understanding phosphorus use efficiency (PUE) in potatoes is vital for maximizing yield while minimizing phosphorus fertilizer wastage. A pot experiment was conducted under greenhouse conditions to evaluate the PUE of commonly grown potato cultivars in South Africa. Four potato cultivars namely Mondial, Sifra, Tyson, and Sababa were used with three different phosphorus application rates: 0 kg P ha-1 (as the control), 145 kg P ha-1, and 205 kg P ha-1. The treatments were replicated three times and arranged in a randomized complete block design, resulting in 36 experimental units. Various plant parameters were collected at the tuber initiation stage and at harvest. Mondial and Sababa outperformed Sifra and Tyson as they had significantly (P < 0.05) higher tuber yields, NDVI values, and PUE. The Mondial cultivar with 145 kg P ha-1 recorded the highest PUE relative to other cultivars. Although Sababa received 205 kg P ha-1 it performed the best in terms of yield (438g) relative to Mondial (391g), Tyson (397g), and Sifra (237g) it’s PUE at lower application rates was significantly (P < 0.05) lower than that of Mondial. This indicates that Mondial is more efficient in P utilisation per kg P applied and can be considered the best-performing cultivar in terms of its PUE. The findings highlight the significant performance of the cultivar Mondial for the potato production industry since it’s an efficient and high-yielding cultivar thus producing higher yield with less fertilizer wastage and lower input cost.
