Crop production in KwaZulu-Natal/Annotated Bibliography

Cropping systems
There is a wide range of cropping systems used by farmers in KwaZulu-Natal, from trench beds of a few square metres to monoculture cropping of sugar cane and maize on farms covering hundreds of hectares.

In 1998 Kirsten and van Zyl stated that "South African agriculture is comprised of mainly two categories of farmers -- the subsistence farmers in the former homeland areas and the large-scale commercial (mainly white) farmers." More recent research (Okunlola et al., 2016; Zantsiet al., 2019; Statistics South Africa, 2005), however, shows that there are many black smallholders that are efficient commercial farmers, and that many commercial farmers are smallholders with annual turnovers of less than R300 000.00.

Monocrop maize, timber and sugar farmers were dominant users of arable land in the region before democratic elections in 1994, but economic and political pressures have resulted in many changes. Many maize grain producers now use no-till and other conservation agriculture (CA) technologies, and rotate maize with soyabean, wheat (where irrigation is possible) and winter forage cover crops. Dairy farmers still produce maize silage on large areas but, again, many have adopted CA, and areas under irrigated perennial pastures have expanded. With lower sugar prices, many sugar cane farmers have diversified; macadamia production is booming, and other horticultural crops are increasing in importance, especially where irrigation is possible.

Kirsten, J.F. and Van Zyl, J., 1998. Defining small-scale farmers in the South African context. Agrekon, 37(4), pp.551-562. PDF

Okunlola, A., Ngubanei, M., Cousins, B. and du Toit, A., 2016. Challenging the stereotypes: Small-scale black farmers and private sector support programmes in South Africa. PDF

Statistics South Africa, 2005. Census of commercial agriculture, 2002. Report No. 11-02-01 (2002). Statistics South Africa, Pretoria. PDF

Zantsi, S., Greyling, J.C. and Vink, N., 2019. Towards a common understanding of ‘emerging farmer’ in a South African context using data from a survey of three district municipalities in the Eastern Cape Province. South African Journal of Agricultural Extension, 47(2), pp.81-93. PDF

Conservation agriculture
No-Till Crop Production For KwaZulu-Natal https://archive.org/details/no-till-crop-production-for-kzn

Introduction to Conservation Agriculture https://www.mahlathini.org/resources/manuals/conservation-agriculture-manual/conservation-agriculture/

No-Till For KwaZulu-Natal's Small-Scale Farming Systems https://archive.org/details/no-till-for-kwa-zulu-natals-small-scale-farming-systems

No-till: Guidelines for beginners This 54-page document is aimed at commercial crop farmers (rather than smallholders) considering conversion to no-till cropping. However, it is included here because it highlights many of the difficulties associated with conservation agriculture and no-till crop production in KwaZulu-Natal. It is available from the No-Till Club of KwaZulu-Natal (the publishers; http://notillclub.com/) and was authored by Aubrey Venter and Ant Muirhead in 2005.

Sithole, N.J., Magwaza, L.S., Mafongoya, P.L. and Thibaud, G.R., 2018. Long-term impact of no-till conservation agriculture on abundance and order diversity of soil macrofauna in continuous maize monocropping system. Acta Agriculturae Scandinavica, Section B—Soil & Plant Science, 68(3), pp.220-229. PDF DOI

Sithole, N.J., Magwaza, L.S. and Thibaud, G.R., 2019. Long-term impact of no-till conservation agriculture and N-fertilizer on soil aggregate stability, infiltration and distribution of C in different size fractions. Soil and Tillage Research, 190, pp.147-156. DOI

Taylor, T.S., Titshall, L.W., Hughes, J.C. and Thibaud, G.R., 2012. Effect of tillage systems and nitrogen application rates on selected physical and biological properties of a clay loam soil in KwaZulu-Natal, South Africa. South African Journal of Plant and Soil, 29(1), pp.47-52. DOI\

Regenerative agriculture
Francis, C.A., Harwood, R.R. and Parr, J.F., 1986. The potential for regenerative agriculture in the developing world. American Journal of Alternative Agriculture, 1(2), pp.65-74. DOI Abstract: Increased food production and greater income for farm families are primary goals of agricultural development in the Third World. Most strategies to achieve these goals are unrealistic in assuming that limited resource farmers can move out of basic food production in multiple cropping systems to high-technology monocropping for export. These strategies are based on petroleum-based inputs that demand scarce foreign exchange. They may include excessive use of chemical fertilizers and pesticides, which adds unnecessary production costs, endangers the farm family, and degrades the rural environment. Dependence on export crops and world markets is economically tenuous, especially for the small farmer. Future agricultural production systems can be designed to take better advantage of production resources found on the farm. Enhanced nitrogen fixation, greater total organic matter production, integrated pest management, genetic tolerance to pests and to stress conditions, and higher levels of biological activity all contribute to resource use efficiency. Appropriate information and management skills substituted for expensive inputs can further improve resource use efficiency. On the whole farm level, appropriate cropping on each field can be integrated with animal enterprises, leading to a highly structured and efficient system. Such systems can serve the needs of national agricultural sector planners, who in many countries are concerned with increased self-reliance in farming inputs and in production of basic food commodities. This includes a realistic focus on training of local development specialists, increased research on food crops under limited resource conditions, and providing information, incentives, and appropriate technologies for operators of both large and small farms. Well-conceived national plans include varied food production strategies and options for farmers with different resource levels.

Kendrick, J., 1985. Regenerative agriculture must be profitable. California Agriculture, 39(7), pp.2-2. PDF Excerpt: Regenerative agriculture should be the goal and practice for all farming in environments where the natural fertility and structure of the soil have been degraded and contaminants have accumulated. Sustainable agriculture should be the goal and practice for all farming where detrimental effects to fertile soils have not yet occurred. In either case, an additional goal is essential in the long run: profitable agriculture."

Lal, R., 2020. Regenerative agriculture for food and climate. Journal of Soil and Water Conservation. DOI PDF Excerpt: "Can regenerative agriculture (RA) produce an adequate amount of nutritious food for the growing and increasingly affluent world population while also reducing and offsetting some anthropogenic emissions? The question may be reframed: how can RA be adapted to produce enough food, be a negative emission technology, and advance Sustainable Development Goals of the United Nations (2015)? System-based RA reconciles the need of producing adequate and nutritious food with the necessity of restoring the environment, making farming a solution to environmental issues. It encompasses a wide range of farming and grazing practices aimed at restoration and sustainable management of soil health through sequestration of soil organic carbon (C). There is no one-size-fits-all practice for diverse soils and ecoregions. RA comprises system-based conservation agriculture (CA), which includes no-till farming in conjunction with residue mulching, cover cropping, integrated nutrient and pest management, complex rotations, and integration of crops with trees and livestock (figure 1) (Lal 2015). RA is all inclusive, and its site-specific package(s) must be fine-tuned in the context of biophysical factors and the human dimensions. RA is soil-centric rather than seed-centric and is based on the premise that “health of soil, plants, animals, and humans is one and indivisible” (Howard 1943; Howard and Howard 1945). In the present context of climate change and environmental issues, it is appropriate to extend the concept by stating that the health of soil, plants, animals, people, and environment is one and indivisible."

Raven, M.R., 2020. Regenerative Agriculture and Implications for Agriculture, Food, and Natural Resources Education. Journal of Agricultural Education, 61(1), pp.1-12. PDF Excerpt: "When I was in my doctoral program in the late 1980s, I was very single minded in becoming a quantitative researcher. I sought out every course I could take on quantitative methods and my vision of the perfect study was one that employed a true experimental design. I now realize that reductionist methodologies are ill suited for studying the grand challenges facing the complex systems that we, as researchers intersect with. Consequently, we need to utilize a mixed methods approach as well as rely on additional methods from other disciplines. I would argue that many of the researchable areas that Agriculture, Food and Natural Resources Education (AFNRE) focuses on would benefit from Participatory research where the community is not being researched but rather a participant in the study with the goal of applying the results to help solve or mitigate the problem. Participatory research falls along spectrum from the extreme end where the community dictates the research questions and methods to the other end where the researchers help formulate the questions while designing the methods and data analysis. Subsequently the researchers assist the community with using the results. Other related methods include the use of modeling and network analysis. Modeling long used by the natural sciences is now a commonly used methodology in the social sciences. Network Analysis is a type of modeling that has specific attributes that makes it a very appropriate modeling methodology that should be employed by AFNRE researchers."

Schreefel, L., Schulte, R.P.O., de Boer, I.J.M., Schrijver, A.P. and van Zanten, H.H.E. '''2020. Regenerative agriculture–the soil is the base.''' Global Food Security, 26, p.100404. PDF Schreefel et al. propose a provisional definition in which regenerative agriculture is defined as: an approach to farming that uses soil conservation as the entry point to regenerate and contribute to multiple provisioning, regulating and supporting ecosystem services, with the objective that this will enhance not only the environmental, but also the social and economic dimensions of sustainable food production. Smuts, J.C., 1927. Holism and evolution. 2nd Edition. Macmillan and Co. London. archive.org Excerpt from the preface to the second edition: "It must be clear to those who look below the surface of things that far-reaching changes in our fundamental ideas and attitudes are setting in, and that the world of to-morrow will be a very different one from that which carried us into the abyss in 1914. In this connection a grave duty arises also for our science and philosophy. The higher thought of our day should not exhaust itself in fine-spun technicalities of speculation or research, but should regard itself as dedicated to service and should make its distinctive contribution towards the upbuilding of a new constructive worldview. We are passing through one of the great transition epochs of history ; we are threatened with reaction on the one hand and with disintegration on the other. The old beacon lights are growing dimmer, and the torch of new ideas has to be kindled for our guidance. The word is largely with our intellectual leaders. In the last resort a civilisation depends on its general ideas; it is nothing but a spiritual structure of the dominant ideas expressing themselves in institutions and the subtle atmosphere of culture. If the soul of our civilisation is to be saved we shall have to find new and fuller expression for the great saving unities the unity of reality in all its range, the unity of life in all its forms, the unity of ideas throughout human civilisation, and the unity of man's spirit with the mystery of the Cosmos in religious faith and aspiration. Holism is in its own way a groping towards the new light and to new points of view. And I cannot help feeling that if the full extent of its implications is realised, both science and philosophy will enter into a more favourable atmosphere for further advance."

Irrigation
Burney, J.A., Naylor, R.L. and Postel, S.L., 2013. The case for distributed irrigation as a development priority in sub-Saharan Africa. Proceedings of the National Academy of Sciences, 110(31), pp.12513-12517. DOI PDF Abstract: Distributed irrigation systems are those in which the water access (via pump or human power), distribution (via furrow, watering can, sprinkler, drip lines, etc.), and use all occur at or near the same location. Distributed systems are typically privately owned and managed by individuals or groups, in contrast to centralized irrigation systems, which tend to be publicly operated and involve large water extractions and distribution over significant distances for use by scores of farmers. Here we draw on a growing body of evidence on smallholder farmers, distributed irrigation systems, and land and water resource availability across sub-Saharan Africa (SSA) to show how investments in distributed smallholder irrigation technologies might be used to (i) use the water sources of SSA more productively, (ii) improve nutritional outcomes and rural development throughout SSA, and (iii) narrow the income disparities that permit widespread hunger to persist despite aggregate economic advancement.

Hadebe, N., 2016. The impact of capital endowment on smallholder farmers’ entrepreneurial drive in taking advantage of small-scale irrigation schemes: case studies from Makhathini and Ndumo B irrigation schemes in KwaZulu-Natal, South Africa (MSc thesis). PDF

Maziya, M., 2013. An assessment of agricultural skills and their effect on agricultural productivity and household food security: a case of Tugela ferry irrigation scheme in KwaZulu-Natal Province of South Africa (MSc thesis). PDF

Mnkeni, P.N.S., Chiduza, C., Modi, A.T., Stevens, J.B., Monde, N., Van der Stoep, I. and Dladla, R., 2010. Best management practices for smallholder farming on two irrigation schemes in the Eastern Cape and KwaZulu-Natal through participatory adaptive research. WRC Report No. TT, 478(10), p.359. PDF

Njoko, S.L., 2014. Smallholder farmers' willingness and ability to pay for improved irrigation: a case of Msinga Local Municipality, KwaZulu-Natal Province (MSc thesis). PDF

Peniston, J., 1908. Irrigation in Natal. Natal Agricultural Journal, 11(12), pp.1558-1560. PDF

Phakathi, S., 2016. Small-scale irrigation water use productivity and its role in diversifying rural livelihood options: case studies from Ndumo B and Makhathini irrigation schemes, KwaZulu-Natal, South Africa (MSc thesis). PDF

Whelan, D., 2019. Water, settlement and food provision in Natal Colony: The Winterton Irrigation Settlement, 1902-1904. Historia, 64(1), pp.42-64. DOI

Weed management
Allemann, L. and Young B.W. 1998. Vegetable Production in KwaZulu-Natal: Weed Control. KwaZulu-Natal Department of Agriculture. Republic of South Africa, Pietermaritzburg. PDF This guideline outlines the importance of weed control in vegetable production and discusses the use of cultural methods and herbicides.

Bàrberi, P., 2019. Ecological weed management in Sub-Saharan Africa: Prospects and implications on other agroecosystem services. In Advances in Agronomy (Vol. 156, pp. 219-264). Academic Press. DOI Abstract: In Sub-Saharan Africa weeds represent a major constraint to food production, and overreliance on herbicides, including toxic ones, is a raising issue. Nonetheless, effective non-chemical weed management practices are adopted by several Sub-Saharan farmers, and may foster ecological intensification and agroecological crop management in the region. Ecological Weed Management (EWM) is a combination of methods aimed to achieve long-term weed suppression through the use of ecological interactions between crop, weeds, soil and/or other taxa fostered by appropriate agroecosystem management, with the least possible use of direct weed control methods, chemical or non chemical. The opportunities offered by EWM in Sub-Saharan Africa are synthesized based on results of a comprehensive literature review. Ecological Weed Management of Striga spp., emblematic parasitic weeds in the area, is treated in details showing that effective methods exist and often work better when combined. These methods include, e.g., the development of cultivars resistant or tolerant of infection, improved crop rotations, cover crops, intercrops and mulches, other soil-based positive interactions, and biocontrol via use of pathogenic fungi. Strategies including functional biodiversity-based methods are expected to foster EWM and overall agroecological crop management in the region. EWM methods can support other agroecosystem services (e.g., soil fertility) and at the same time be improved by methods aiming at other services (e.g., push-pull strategies against maize cob borers). Transdisciplinary collaboration and scientists' engagement in participatory research and action with farmers and other stakeholders would be instrumental to facilitate broader adoption of EWM in Sub-Saharan Africa.

Bezuidenhout, S.R., Reinhardt, C.F. and Whitwell, M.I., 2012. Cover crops of oats, stooling rye and three annual ryegrass cultivars influence maize and Cyperus esculentus growth. Weed Research, 52(2), pp.153-160. DOI Abstract: No information is available on the effect of cover crops on weed growth in maize production in KwaZulu‐Natal, South Africa. In a field experiment, the influence of two preceding cover crops, stooling rye and annual ryegrass, on the growth of maize and the weed Cyperus esculentus were compared with herbicides and weed control by hoeing. Maize emergence and early growth were delayed in the presence of physical residues of both cover crop species, especially annual ryegrass. Growth of C. esculentus was significantly inhibited in the inter‐row maize planting lines by the cover crops for the first 16 days after maize emergence, but this effect had diminished by day 28. In a pot experiment, the influence of the same two cover crops on maize and C. esculentus growth was evaluated together with oats and two additional annual ryegrass cultivars. Here, the growth of maize and C. esculentus were suppressed, especially by the root residues of the annual ryegrass, in particular the cultivar Midmar. Chemical analysis of the leachate of the root residues indicated the presence of phenolic acids and benzoxazolin‐2(3H)‐one. To achieve effective weed control, a weed management strategy combining the mulch retained on the soil surface, with a possible reduction in the type and amount of herbicide, should be implemented.

Bezuidenhout, S.R. 2015. Sprayer calibration. Research & Technology Bulletin 2015/10, KwaZulu-Natal Department of Agriculture and Rural Development. Republic of South Africa, Pietermaritzburg. PDF A four-page document describing how to calibrate agrochemical spraying equipment. It includes sections on nozzle selection, water quality, and details of calculations used to calibrate knapsack sprayers and boom sprayers.

Bezuidenhout, S.R. 2016. Weed management principles for maize. KwaZulu-Natal Department of Agriculture and Rural Development Research and Technology Bulletin, 2016/04. PDF

Bezuidenhout, S.R. 2016. Growth and development of Cyperus esculentus. KwaZulu-Natal Department of Agriculture and Rural Development Research and Technology Bulletin, 2016/01. PDF

Joubert, A.B.D. 2000. Weed control by smallholder farmers in Ciskei, Eastern Cape Province, South Africa. ''Animal power for weed control. A resource book of the Animal Traction Network for Eastern and Southern Africa (ATNESA). Publication of Technical Centre for Agricultural and Rural Cooperation (CTA), Wageningen, The Netherlands'', pp.214-217. PDF Abstract: A literature study was undertaken on the weeding of maize on smallholder farms in Ciskei, South Africa. Most weeding under these conditions is carried out by hand pulling and/or hoeing. Only limited use is made of animal traction, and large-scale development of this method will not be possible until the conventional broadcast method of planting maize has been replaced by row planting. Lee, N. and Thierfelder, C., 2017. '''Weed control under conservation agriculture in dryland smallholder farming systems of southern Africa. A review.' Agronomy for Sustainable Development, 37''(5), p.48. PDF Abstract: Human-induced soil degradation has led to declining yields and soil fertility in many parts of the world. Conservation agriculture has been proposed as a strategy to ensure more sustainable land use. While conservation agriculture, based on minimum soil disturbance, crop residue retention, and diversification may improve a range of soil characteristics and can be a potential cropping system for improving farmer resilience to climate change, increased weed pressure is often an impediment to its widespread adoption in southern Africa. Weed control under conservation agriculture in other countries has been linked to increased herbicide use, but concerns about herbicide resistance, access to chemicals, and environmental impacts highlight the need for alternative weed control strategies accessible for smallholders. Farmers in semi-arid regions contend with the additional challenge of low biomass production, which may limit the weed-suppressing benefits of permanent soil cover. This paper reviews the regional applicability of various mechanical (manual weeding, weeding using animal traction, weed seed harvest), thermal (soil solarization, weed steaming, flaming), chemical (herbicides, seed coating), and cultural (crop competition, crop residue retention, intercropping, crop rotation) weed control strategies. For each strategy, benefits and challenges were assessed and contextualized with the circumstances of rainfed smallholder farmers in southern Africa. We found that (1) no single solution can solve all weed control challenges under current conservation agriculture systems; (2) success of weed control strategies is largely contingent upon site-specific conditions, including soil type, dominant weed species, and socioeconomic factors; and (3) practices new to southern Africa, such as weed steaming, merit localized research. Previous reviews have addressed various weed control strategies, but a comprehensive review of strategies available to smallholder farmers in semi-arid southern Africa is lacking. Finding a suitable combination of weed control strategies is critical for encouraging smallholder farmers to adopt and maintain conservation agriculture practices.

Sims, B., Corsi, S., Gbehounou, G., Kienzle, J., Taguchi, M. and Friedrich, T., 2018. Sustainable weed management for conservation agriculture: Options for smallholder farmers. Agriculture, 8 (8), p.118. DOI Abstract: Land degradation and soil fertility deterioration are two of the main causes of agricultural production stagnation and decline in many parts of the world. The model of crop production based on mechanical soil tillage and exposed soils is typically accompanied by negative effects on the natural resource base of the farming environment, which can be so serious that they jeopardize agricultural productive potential in the future. This form of agriculture is destructive to soil health and accelerates the loss of soil by increasing its mineralization and erosion rates. Conservation agriculture, a system avoiding or minimizing soil mechanical disturbance (no-tillage) combined with soil cover and crop diversification, is considered a sustainable agro-ecological approach to resource-conserving agricultural production. A major objective of tillage is supposed to be weed control, and it does not require very specific knowledge because soil inversion controls (at least temporarily) most weeds mechanically (i.e., by way of burying them). However, repeated ploughing only changes the weed population, but does not control weeds in the long term. The same applies to the mechanical uprooting of weeds. While in the short term some tillage operations can control weeds on farms, tillage systems can increase and propagate weeds off-farm. The absence of tillage, under conservation agriculture, requires other measures of weed control. One of the ways in which this is realized is through herbicide application. However, environmental concerns, herbicide resistance and access to appropriate agro-chemicals on the part of resource-poor farmers, highlight the need for alternative weed control strategies that are effective and accessible for smallholders adopting conservation agriculture. Farmers in semi-arid regions contend with the additional challenge of low biomass production and, often, competition with livestock enterprises, which limit the potential weed-suppressing benefits of mulch and living cover crops. This paper reviews the applicability and efficacy of various mechanical, biological and integrated weed management strategies for the effective and sustainable management of weeds in smallholder conservation agriculture systems, including the role of appropriate equipment and prerequisites for smallholders within a sustainable intensification scenario.

Soil fertility
Farina, M.P.W. and Channon, P., 1988. Acid‐subsoil amelioration: I. A comparison of several mechanical procedures. Soil Science Society of America Journal, 52(1), pp.169-175.DOI PDF Abstract: In many high potential cropping areas, particularly of the tropics and subtropics, crop exploitation of subsoil moisture reserves is prevented or severely curtailed by high levels of exchangeable Al. Since the effects of surface incorporated lime on subsoil acidity are minimal in most highly weathered soils, specialized mechanical and/or chemical procedures are required to overcome the problem. This work was conducted in order to assess the practicalities of mechanical profile modification and to compare the efficacy of several possible procedures. In a field experiment with maize (Zea mays L.) on a strongly acidic Plinthic Paleudult conventional moldboard incorporation of lime was compared to lime incorporation using a deep moldboard plow, the Wye‐double‐digger, a modified subsoiler capable of incorporating vertical bands of ameliorated topsoil to depths of 0.7 m, and a deep limer designed to ameliorate vertical bands of soil to a similar depth. All the procedures tested proved superior to conventional liming, the average response to profile modification ranging from over 1 400 kg ha 1 in a season in which severe moisture stress was experienced to approximately 400 kg ha−1 in an exceptionally high rainfall season. Yield responses were related to increases in rooting volume and to changes in root configuration. Segmental liming proved as effective as deep plowing or double digging.

Farina, M.P.W. and Channon, P., 1988. '''Acid‐subsoil amelioration: II. Gypsum effects on growth and subsoil chemical properties.' Soil Science Society of America Journal, 52''(1), pp.175-180.DOI PDF Abstract: In many highly weathered soils crop exploitation of subsoil moisture reserves is severely curtailed by toxic levels of Al. Since vertical movement of lime is usually extremely slow in such soils, specialized mechanical and/or chemical procedures are required to overcome the problem. A field experiment with maize (Zea mays L.) on a strongly acidic Plinthic Paleudult examined the effects of surface‐incorporated gypsum on yield, root development, and profile chemical properties for four cropping seasons. The effects of gypsum (10 Mg ha−1) were time dependent, but by the fourth season had resulted in a cumulative grain yield gain of 3.4 Mg ha−1. Progressive depressions in the level of exchangeable Al were accompanied by increases in subsoil Ca, Mg, and SO4‐S. Water pH increased markedly in the zone of maximum SO4‐sorption/precipitation, but pH determined in KCl remained unchanged. By the fourth season the effects of gypsum on subsoil root development were striking. These results indicate that surface incorporation of gypsum is an economically viable approach to subsoil amelioration on soils such as that studied here.

Farina, M.P.W., 1997. Management of subsoil acidity in environments outside the humid tropics. Plant–soil interactions at low pH: sustainable agriculture and forestry production. Brazilian Soil Sci Soc, Campinas, pp.179-190. PDF Subsoil acidity, both natural and anthropogenic, is an important yield-limiting factor for agriculture in vast areas of the world. Although more widespread in the moist tropics, strongly acidic subsoils occur over a surprisingly diverse spectrum of climatic conditions. This review examines subsoil acidity and its management in areas generally drier and cooler than the the humid tropics. Here, acid subsoils are more localized, Al toxicity is more important than Ca deficiency, and reserve acidity often makes the amelioration of subsoil acidity particularly demanding. The economic viability of approaches used with great success in the moist tropics is often tenuous in the less humid subtropics, and alternative ameliorative or avoidance strategies must be considered.These include the use of specialized tillage practices, exploitation of differential crop tolerance to acidity and careful N use. Findings from long-term field experiments are used to illustrate the potential benefits to be derived from such strategies.

Farina, M.P.W. and Channon, P., 1991. A field comparison of lime requirement indices for maize. Plant and Soil, 134(1), pp.127-135. DOI PDF Abstract: Due, in part, to the relative paucity of published comparisons based on field generated data, there is still poor agreement regarding the relative merits of lime requirement indices based on exchangeable Al and those based on pH. The objective of this study was to compare such indices using results obtained from long-term field experiments. Data were obtained over 22 site-years from lime trials conducted on clay (Typic Haplorthox) and sandy loam (Plinthic Paleudult) soils differing widely in organic carbon content. Relative maize (Zea mays L.) yields were used to compare the prognostic value of soil pH with indices obtained using exchangeable Al and exchangeable acidity (Al+H). Both within and across soils, pH proved to be markedly inferior to Al based indices. Exchangeable acid saturation of the effective cation exchange capacity, a readily obtained and popular index of lime requirement in some countries, proved as effective as less easily acquired indices based on exchangeable Al per se. The findings reported are consistent with those of many glasshouse studies and support the viewpoint that indices based on Al or acid saturation should replace pH as a measure of lime requirement.

Farina, M.P.W., Thibaud, G.R. and Channon, P., 1997. Factors affecting the response of soyabean to molybdenum application. Final Report, ARC Grain Crops Institute, Cedara, South Africa. PDF

Fey, MV, Manson, AD & Schutte, R., 1990. Acidification of the pedosphere. South African Journal of Science, 86(7), p.403-406. PDF Abstract: Acidification is greatly intensified by anthropogenic distortions of the N and S cycles, and by afforestation and the export of bases in harvested products. The rate of soil acidification is potentially highest in agriculture, where it is associated mainly with the liberal use of ammonia fertilizers and the production of forage legumes. Where exotic tree species have been planted, the acidification rate is slower but a comparison of some recently published data suggests that afforestation may speed up soil acidification even more than the worst recorded acid rain on the eastern Transvaal highveld. Projected climatic and atmospheric changes during the next half century are unlikely to intensify greatly the acidification process.

Ichami, S.M., Shepherd, K.D., Hoffland, E., Karuku, G.N. and Stoorvogel, J.J., 2020. Soil spatial variation to guide the development of fertilizer use recommendations for smallholder farms in western Kenya. Geoderma Regional, p.e00300. DOI A 10000-ha block of land in western Kenya was sampled to investigate the spatial variation in maize grain yields in relation to soil fertility parameters (organic C, total N, P and extractable cations). Soil organic C was found to be a key soil property that influenced maize yield; it varies over short distances in maize fields of the region. It was suggested that fine-scale digital soil maps could help refine fertilizer recommendations.

Johnston, M.A., Farina, M.P.W. and Lawrence, J.Y., 1987. Estimation of soil texture from the sample density. Communications in soil science and plant analysis, 18(11), pp.1173-1180. DOI PDF This paper shows that the density of dried and milled soil samples can be used to estimate the clay content of soils sampled in KwaZulu-Natal.

Manson, A.D., 2020. Soil acidity and liming in KwaZulu-Natal. Research & Technology Bulletin 2020-21/03. KwaZulu-Natal Department of Agriculture & Rural Development, Pietermaritzburg, South Africa. DOI PDF Acid soils are very common in KwaZulu-Natal and yields of crops and vegetables are often poor where soil pHKCl is less than 4.5. There are differences between the various vegetables and crops with respect to their abilities to grow on acid soils. Amelioration of soil acidity with agricultural limestone is often cost-effective, and is best done based on soil tests. Photographs of several acidity-related symptoms are included.

Manson, A.D. & Findlay, N., 2015. Agricultural uses of lime and gypsum. Research & Technology Bulletin 2015/13. KwaZulu-Natal Department of Agriculture and Rural Development. Republic of South Africa, Pietermaritzburg. DOI PDF Agricultural limestone (lime) and gypsum are used in agriculture as soil ameliorants. This short document outlines different situations where their application is appropriate.

Manson, A.D., Miles, N. & Farina, M.P.W., 2017. FERTREC Notes and Norms: Explanatory notes and crop and soil norms for the Cedara computerized fertilizer advisory service. KwaZulu-Natal Department of Agriculture and Rural Development. Republic of South Africa, Pietermaritzburg. DOI PDF The fertilizer recommendation service of the KwaZulu-Natal Department of Agriculture and Rural Development is based on soil analysis. This document details the procedures used to interpret soil analyses and produce fertilizer and lime recommendations based on those analyses; these procedures were developed using the results of over 30 years of field and laboratory calibration research in KwaZulu-Natal.

Roberts, V. G., Adey, S. & Manson, A. D., 2003. An investigation into soil fertility in two resource-poor farming communities in KwaZulu-Natal (South Africa). South African Journal of Plant and Soil 20, 146-151. DOI PDF Low soil fertility is one of the major constraints affecting resource-poor farmers in KwaZulu-Natal. However, nutrient depletion status is field specific. This paper investigates the hypothesis that among KwaZulu-Natal resource-poor farmers' fields, the fields closer to the homestead are more intensively managed and that this is reflected in the fertility status of these fields. This study indicates the higher fertility status and better management of ‘homefields’ in comparison to ‘outfields’, and reflects different management systems being used in resource-poor farmers' fields. Also highlighted is the need to sample individual fields to make cost-effective fertilizer and lime recommendations, rather than making blanket recommendations in districts or wards.

Schroeder, B.L., Farina, M.P.W. and Fey, M.V., 1985. A comparison of several nitrogen-availability indices on four Natal maize-producing soils. South African Journal of Plant and Soil, 2(3), pp.164-166. DOI PDF

Sumner, M.E. and Farina, M.P., 1986. Phosphorus interactions with other nutrients and lime in field cropping systems. In Advances in soil science (pp. 201-236). Springer, New York, NY. DOI PDF Abstract: A survey of recently published textbooks and journal papers in the field of soil fertility and plant nutrition indicates that the authors seldom see fit to devote much attention to the interplay between nutrients in relation to yield enhancement in field cropping systems. This is a reflection of the widely adopted approach of varying only one or possibly two nutrients at a time in field experimentation. Without factorial designs involving a number of nutrient factors at varying levels, serious study of interactions is not possible. Until field research in soil fertility pays greater attention to the multifactor approach, there will be little prospect of verifying the large number of nutrient interactions previously studied under greenhouse or solution culture conditions.

Thibaud, G.R., 2000. NPK fertilization and liming for no-till. In: Guide to No-till crop production in KwaZulu-Natal. No-till Club, Howick, South Africa.

Thibaud, G.R., 2014. Soil Acidity and Fertiliser Management in Conservation Agriculture. Paper presented at the Fertasa Soil Fertility and Plant Nutrition Symposium, 2014. PDF

Pest and disease management
https://mahlathini.org/resources/manuals/natural-pest-and-disease-control/natural-pest-and-disease-control-handbook_final_ek_jan-2012/

EPA. 2020. Integrated Pest Management (IPM) Principles www.epa.gov

Wikipedia. 2020. Integrated pest management en.wikipedia.org

Gumede, H. 2015. Storage and safe use of agrochemicals - How much do you know? KwaZulu-Natal Department of Agriculture and Rural Development Research and Technology Bulletin, 2015/11. PDF

Diseases
Nunkumar, A. 2018. Management of plant pathogens in irrigation water. KwaZulu-Natal Department of Agriculture and Rural Development Research and Technology Bulletin, 2018-19/06. PDF

Nunkumar, A. 2017. Banana bunchy top disease: A threat to the banana industry. KwaZulu-Natal Department of Agriculture and Rural Development Research and Technology Bulletin, 2017-18/04. PDF

Nunkumar, A. 2017. Mycotoxins: A threat to animal and human health. KwaZulu-Natal Department of Agriculture and Rural Development Research and Technology Bulletin, 2017-18/03. PDF

Nunkumar, A. 2016. The correct use and application of fungicides. KwaZulu-Natal Department of Agriculture and Rural Development Research and Technology Bulletin, 2016-17/11. PDF

Nunkumar, A. 2015. Disease management in crops. KwaZulu-Natal Department of Agriculture and Rural Development Research and Technology Bulletin, 2015/19. PDF

Moodley, S. 2015. The application of plant based pesticides in sustainable agriculture. KwaZulu-Natal Department of Agriculture and Rural Development Research and Technology Bulletin, 2015/08. PDF

Insects
Nunkumar, A. 2017. Aphid monitoring on Cedara. KwaZulu-Natal Department of Agriculture and Rural Development Research and Technology Bulletin, 2017-18/09. PDF

Bezuidenhout, S.R. 2017. The tomato leaf miner, Tuta absoluta. KwaZulu-Natal Department of Agriculture and Rural Development Research and Technology Bulletin, 2017-18/05. PDF

Bezuidenhout, S.R. and Nunkumar, A. 2017. Chemical control options for Fall Armyworm in maize. KwaZulu-Natal Department of Agriculture and Rural Development Research and Technology Bulletin, 2016-17/09. PDF

Villa Crop. 2021. Fall Armyworm Mitigation. https://agritraining.co.za/fall-armyworm-faw-free-learning-modules/

Nematodes
Coyne D.L., Cortada L., Dalzell J.J., Claudius-Cole A. O., Haukeland S., Luambano N., Herbert Talwana H. (2018) Plant-Parasitic Nematodes and Food Security in Sub-Saharan Africa. Annual Review of Phytopathology, 56, DOI

Vegetables in KwaZulu-Natal
Allemann, L. and Young B.W. 1998. Vegetable Production In A Nutshell. Department of Agriculture, South Africa. Pretoria. PDF Crop-specific guidelines are given for a range of vegetable crops grown in South Africa, along with general fertiliser guidelines. Suitable climate, soil types, cultivars, sowing times, seeding rates, plant population and spacing are outlined, and brief indications are given regarding the required fertiliser, possible pests and diseases, and likely yields. Vegetables included are beetroot, brinjal (eggplant), cabbage, carrot, chilli (hot pepper), trailing cucurbits (butternut, gem squash, hubbard squash, pumpkin), green bean (bush type), green pea, lettuce, amadumbe (taro), onion, potato, sweet pepper, sweet potato, swiss chard, and table tomato.

Allemann, L. and Young B.W. 1998. Vegetable Production in KwaZulu-Natal: Weed Control. KwaZulu-Natal Department of Agriculture. Republic of South Africa, Pietermaritzburg. PDF This guideline outlines the importance of weed control in vegetable production and discusses the use of cultural methods and herbicides

Fruit and nut crops in KwaZulu-Natal
Sheard, A.G., Allemann, L. and Young, B. 2006. Fruit and Nut Production in KwaZulu-Natal. KwaZulu-Natal Department of Agriculture and Environmental Affairs. PDF This document gives a range of recommendations for the production of 18 different fruits and nuts in KwaZulu-Natal. These include fruit suited to the subtropical coastal zones (such as mango and litchi) to those that require the cooler climate of the highlands of the province (such as apple, peach and nectarine); also included are avocado, banana, citrus, granadilla, papaya, pineapple, sweet cherry, macadamia, pecan, strawberry, raspberry, blackberry and blueberry. Details regarding the natural resource (climate and soil) requirements are given for each crop. Outlines of the management requirements for each species include information on planting times, bearing age, plant spacing, fertilization, irrigation, possible yields, pests, diseases and suitable varieties.

Sheard, A.G. and Kaiser, C. 2001. Integrated pest & disease management (IPDM) of apples & pears in KwaZulu-Natal. KZN Agri Report No. 2001/05. KwaZulu-Natal Department of Agriculture and Environmental Affairs, South Africa. Pietermaritzburg. PDF

Forage crops
Kikuyu, ryegrass, lucerne, white clover, Eragrostic curvula, Cynodon species.

Voigt, P.W. and Mosjidis, J.A., 2002. Acid‐soil resistance of forage legumes as assessed by a soil‐on‐agar method. Crop Science, 42(5), pp.1631-1639.

Hemp Cannabis sativa
Adesina, I., Bhowmik, A., Sharma, H. and Shahbazi, A., 2020. A Review on the Current State of Knowledge of Growing Conditions, Agronomic Soil Health Practices and Utilities of Hemp in the United States. Agriculture, 10(4), p.129. DOI PDF

Finnan, J. and Burke, B., 2013. Potassium fertilization of hemp (Cannabis sativa). Industrial Crops and Products, 41, pp.419-422. DOI

Iványi, I. and Izsáki, Z., 2009. Effect of nitrogen, phosphorus, and potassium fertilization on nutrional status of fiber hemp. Communications in soil science and plant analysis, 40(1-6), pp.974-986. https://www.tandfonline.com/doi/abs/10.1080/00103620802693466 PDF]

Jordan, H.V., Lang, A.L. and Enfield, G.H., 1946. Effects of Fertilizers on Yields and Breaking Strengths of American Hemp, Cannabis Sativa L. Agronomy Journal, 38(6), pp.551-562. DOI

Papastylianou, P., Kakabouki, I. and Travlos, I., 2018. Effect of nitrogen fertilization on growth and yield of industrial hemp (Cannabis sativa L.). Notulae Botanicae Horti Agrobotanici Cluj-Napoca, 46(1), pp.197-201. http://www.notulaebotanicae.ro/index.php/nbha/article/view/10862 PDF]

Struik, P.C., Amaducci, S., Bullard, M.J., Stutterheim, N.C., Venturi, G. and Cromack, H.T.H., 2000. Agronomy of fibre hemp (Cannabis sativa L.) in Europe. Industrial crops and products, 11(2-3), pp.107-118. PDF

Tang, K., Struik, P.C., Yin, X., Calzolari, D., Musio, S., Thouminot, C., Bjelková, M., Stramkale, V., Magagnini, G. and Amaducci, S., 2017. A comprehensive study of planting density and nitrogen fertilization effect on dual-purpose hemp (Cannabis sativa L.) cultivation. Industrial Crops and Products, 107, pp.427-438. PDF

Van der Werf, H.M.G. and Van den Berg, W., 1995. Nitrogen fertilization and sex expression affect size variability of fibre hemp (Cannabis sativa L.). Oecologia, 103(4), pp.462-470. PDF

Vessel, A.J. and Black, C.A., 1947. Soil type and soil management factors in hemp production. Iowa Agriculture and Home Economics Experiment Station Research Bulletin, 28(352), p.1. PDF These authors found that good internal drainage is a soil property required for hemp production - several old photographs are included as evidence.

Medicinal plants
Williams, V.L., Victor, J.E. and Crouch, N.R., 2013. Red listed medicinal plants of South Africa: status, trends, and assessment challenges. South African Journal of Botany, 86, pp.23-35. DOI PDF

Traditional crops
Manyoni, N.N. 2017. The super nutritious Cloeme gynandra L. KwaZulu-Natal Department of Agriculture and Rural Development Research and Technology Bulletin, 2017-18/08. PDF

Mbotho, K. and Ndayi, P. 2015. Purslane: a weed with a potential for human consumption and animal feed. KwaZulu-Natal Department of Agriculture and Rural Development Research and Technology Bulletin, 2015/21. PDF

Oyster mushroom production
Macdonald, C.I.,Van Rij, N.C. and Mncwabe, M. 2011. Basic guidelines for oyster mushroom pack production using Juncao technology in KwaZulu-Natal. KwaZulu-Natal Department of Agriculture and Rural Development Research and Technology Bulletin, 2011/01. PDF

Macdonald, C.I., Zhanxi, L. and Hui, L. 2010. Giant Juncao grass cultivation in KwaZulu-Natal. KwaZulu-Natal Department of Agriculture and Rural Development Research and Technology Bulletin, 2010/10. PDF

Macdonald, C.I., Zhanxi, L., Hui, L. and Dongmei, L. 2010. Upland rice production in KwaZulu-Natal. KwaZulu-Natal Department of Agriculture and Rural Development Research and Technology Bulletin, 2010/09. PDF

Macdonald, C.I., Zhanxi, L., Hui, L. and Dongmei, L. 2010. Basic guidelines for oyster mushroom fruiting management in KwaZulu-Natal. KwaZulu-Natal Department of Agriculture and Rural Development Research and Technology Bulletin, 2010/08. PDF

Van Rij, N.C. Macdonald, C.I. and Mncwabe, M. 2012. Guidelines to poisonous mushrooms in KwaZulu-Natal. KwaZulu-Natal Department of Agriculture and Rural Development Research and Technology Bulletin, 2012/01. PDF

Van Rij, N.C. Macdonald, C.I. and Mncwabe, M. 2012. Umhlahlandlela wamaKhowe anobuthi KwaZulu-Natal. KwaZulu-Natal Department of Agriculture and Rural Development Research and Technology Bulletin, 2012/01. PDF