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Future plant nutrition research within a global context

 

The world's requirements for more protein, especially in the form of meat, as well as the increase in mass production of crops for biofuel, have added to the complexity of the challenge. Agricultural production will have to increase by 60% and 90% of that increase will lie in enhancing production efficiency and intensity. Such enhancement of production will include a better understanding and management of plant nutrition as a primary objective, as 50% of the world is currently fed on produce from fertilized lands. As Per Pinstrup-Anderson, then Director General of the International Food Policy Research Institute (FPRI) put it in 2000: "As long as agriculture remains a soil-based industry, major increases in productivity are unlikely to be attained without ensuring that plants have an adequate and balanced supply of nutrients."

From 1960 to 2020 the world population will have tripled and the available land for food production will have halved. To add to the dilemma, world per capita cereal production, despite the current steady growth of maize production of 120 kg per ha per year, did not increase. It actually decreased from 374 kg/capita in 1985 to 340 kg/capita in 2007 (Figures 1 and 2).

FIGURE 1:

Historical USA maize grain yields (t/ha) 1866 to date. South African data is super-imposed.

Historical USA maize grain yields (t/ha) 1866 to date [graph]

USA graph from Nielsen, 2012 and RSA data from Van Biljon, 2009

FIGURE 2:

Kilogram cereal produced per capita over time. Data calculated from the Food and Agriculture Organization of the United Nations (FAO) and the UN (United Nations) publicly available data

Kilogram cereal produced per capita over time [graph]

Another dimension has been added over recent time and that is the concept of farming for health - not only to improve yield, soil fertility, profitability and reduce environmental impact, but also to enhance human health. The new objective is not only food security (kilojoules), but also nutrition security (supply of all essential nutrients).

In an African context, it is ironic that Sub-Saharan Africa, which is looked at as the base for future additional food production (some say that 70% of the growth in production will come from this continent), only uses on average approximately 6 kg of fertilizer per hectare and is regarded as containing the largest area of physical and economic water scarcity.

Against this background and its huge challenges, a fertilizer company needs to position itself strategically and commit itself to investment in plant nutrition and agronomic research, not only to meet said challenges, but also to gain and maintain a competitive advantage in a harsh commercial international environment by contributing in real terms on the farm. Omnia Fertilizer currently invests approximately 30 million Rand (ZAR) in plant nutrition research per annum to meet the aforementioned challenges. In the following paragraphs, the primary research fields relating to plant nutrition requirements for the immediate future, as identified by world organisations and Omnia Fertilizer, with specific reference to grain crops, will be briefly mentioned.

Water use efficiency

Enhanced water use efficiency is by far the aspect most identified by international researchers to make a difference to food production. Certain forms of fertilizer, for instance nitrates, enhance water use efficiency. The correct management of fertilizer also enhances water use efficiency of crops. One example is the fact that efficient fertilization of pastures can halve the water requirements for the production of one unit of beef.

The other side of the coin is that nutrient use efficiency is substantially enhanced by effective irrigation and soil moisture management.

Nutrient use efficiency, especially nitrogen

The second most important factor emerging from international publications to make a difference in food production is nutrient use efficiency, especially nitrogen. It has been shown that nitrogen use efficiency is approximately 40% on commercial farms in developed countries, but field trials done by the same countries have shown that efficiency rates of higher than 80% are possible. Ohio State University in the USA has shown that nitrogen use efficiency in maize could be enhanced from 45% to 80% by applying higher potassium levels than is accepted as the usual norm. The US has shown the efficiency of use of nitrogen on maize as currently being 70 kg of maize grain produced per kilogram nitrogen (Figure 3). Omnia Fertilizer trials have proven in South Africa that it is possible to produce 113 kg of maize grain per kg of nitrogen applied on a sandy soil by using differential application.

It is clear that there is no silver bullet regarding nitrogen management, but that an integrated approach should be followed accommodating a magnitude of factors.

FIGURE 3:

Nitrogen Partial Factor Productivity (PFPN) or nitrogen use efficiency over time in two countries. Redrawn from Maene, 2010.

Nitrogen Partial Factor Productivity (PFPN) or nitrogen use efficiency over time [graph]

Best management practices and fully balanced nutrition

This age old but still developing field of research is based on the often quoted 4R approach, meaning applying the right product at the right rate, time and place. Sound practices of the past such as fully balanced nutrition and liming programmes need to build on (Figure 4), but more nutritional elements and their interaction need to be considered than in the past. For instance, there are now officially 17 elements regarded as essential for plant nutrition. Chloride and nickel have been added to the well-known list. There are also the so-called beneficial elements: aluminium, cobalt, sodium, selenium and silicon which need to be considered. Plant nutritional elements also impact on soil life, which is a most important aspect in sustainable systems. New methods of plant and soil analysis and element quantification are emerging that need to be used to the full extent. Also, for instance, new cultivars bred for drought tolerance and enhanced nitrogen use efficiency will become more prominent and will have to receive special attention regarding nutrition.

FIGURE 4:

Long term effect of balanced fertilization on wheat yield (Redrawn from IFPRI, 2000).

Long term effect of balanced fertilization on wheat yield [graph]

Nutrition strategies for conservation tillage systems

Linking to the previous point, good management includes the use of cover crops and soil conservation measures, the addition of organic matter to the soil and the judicious use of chemical fertilizers, pesticides and farm machinery.

It is, however, clear that no matter what conservation tillage system is to be followed - from limited tillage, strip till or pure no-till or direct seeding - the base of adequate plant nutrition or soil fertility needs to be set with the absolute necessity of having to address any possible soil physical constraints. Defining such fertility thresholds and maintenance in different crop rotation scenarios is a major challenge.

Understanding the dynamics and efficiency of nutrients in increased mulch and trash systems is also essential.

Precision farming and risk management

Technology in the field of precision farming is developing at a staggering pace. In most cases the basic understanding and use of this technology, never mind its application, is poorly understood. One aspect is for instance that zone management regarding soil fertility should follow zone identification based on soil physical parameters, water holding capacity and drainage. Precise and variable rate application of ameliorants, fertilizer and seed bring more challenges. The greatest task at hand is the management and maximum use of huge databases or "big data" to make a real difference at farm field level. Spatial interpretation of such integrated databases with geographic information systems, especially to identify and quantify risk, not only regarding plant nutrition, will be absolutely essential.

Proximal and remote sensing is developing fast as well. New sensors (also for nutrients) are emerging on the nano-technology front and these will be integrated in precision farming systems.

Product efficiency and environmental impact

Each fertilizer company will have to optimise its product efficiency to meet the new challenges, from factory to field. According to international publications, slow and controlled release fertilizers, stabilised fertilizers, fertilizers supplemented with trace elements and soluble / liquid fertilizers will continue to receive primary attention. With the emphasis on environmental impact of fertilizer and water use efficiency, renewed attention is given to nitrate based fertilizers. For instance, it is a published fact that ammonium nitrate has 25% less impact on greenhouse gas production (CO2) per unit nitrogen than urea, and that nitrates enhance the water use efficiency of plants substantially (see below).

Elicitors and biostimulants

An elicitor is a substance that triggers a resistance and /or hypersensitive response in a plant. Specific nutrients (essential or beneficial) may act as elicitors. Elicitors activate genes involved in the defense response of plants.

Agricultural biostimulants include diverse formulations of compounds and other products that are applied to plants or soils to regulate and enhance the crop's physiological processes, thus making them more efficient. The important fact is that crop bio-stimulation is complementary to crop nutrition and crop protection.

As the world of plant nutrition, stimulants and pesticides move closer to each other, the understanding of the above relatively new concepts and their application is important.

Nanotechnology

This is probably the most misunderstood and misquoted technology under development today.

Nobel laureate Richard Smalley presented the benefits of nanotechnology to the USA House Committee on Science in 1999. He emphasized that the impact of nanotechnology on health, wealth and lives of the people will be at least equal to the combined influences of micro-electronics, medical imaging, computer-aided engineering and man-made polymers developed in the 20th century.

The literature pertaining to the role of nanotechnology in plant and soil systems demonstrates that nano materials may assist in the controlled release of agro-chemicals for nutrition and protection against pests and pathogens, delivery of genetic material, sensitive detection of plant disease and pollutants and the formation of soil structure.

Understanding the "cross talk" between nutrients, plant physiology and soil micro-organisms

This fascinating emerging field of research at molecular level poses many opportunities and offers explanation to many field observed phenomena. Recent publications for instance explain why sulphur nutrition of plants generate the plant hormones auxin and jasmonate and why there is a link between nitrate feeding and iron acquisition, as well as several hormones such as abscisic acid responsible for the regulation of water in the plant.

A part of this front of research is also understanding the rhizosphere interaction with soil microbial populations to stimulate nutrient uptake and also to generate specific hormones.

Making a difference on the farm

Omnia Fertilizer's aim is to maximise its customer's prosperity (reduce risk and increase marketable yield and quality) by leveraging knowledge. Investing in such knowledge, but not making it practical on the farm is futile. Producer participation, collaboration with other entities and disciplines and most important, technology transfer, is essential. One such example is the current multidisciplinary strip trials Omnia Fertilizer is involved in as co-worker and sponsor with Grain SA. Omnia Fertilizer strives to bring real applicable knowledge to the South African farmer and also to farmers in other countries where Omnia is present, by placing multiple feet on the farm and so, hopefully, also to contribute in a small way to feeding the world of tomorrow.

References:

  • IFPRI/FAO, 2009. Discussion paper 32: Integrated nutrient management, soil fertility and sustainable agriculture: Current issues and future challenges. Published by IFPRI, Washington DC. ISBN 0-89629-638-5
  • MAENE, L. 2010. Identifying and examining the current challenges and opportunities faced by the fertilizer industry. An IFA web-based publication. www.ifa.com
  • NIELSON, R.L. 2012. Advanced farming systems and new technologies for the maize industry. FAR conference, Hamilton, New Zealand. Published by Purdue University. 15 pages
  • VAN BILJON, J.J. 2009. Maize yield and fertilizer research over the last fifty years: An overview. FSSA Journal, June edition p.37-50