A.J. Haverkort

Climate Change and Potato Production in Contrasting South African Agro-Ecosystems 3. Effects on Relative Development Rates of Selected Pathogens and Pests

A set of daily weather data simulations for 1961 to 2050 were used to calculate past and future trends in pest and disease pressure in potato cropping systems at three agro-ecologically distinct sites in South Africa: the Sandveld, the Eastern Free State and Limpopo. The diseases and pests modelled were late blight, early blight and brown spot, blackleg and soft rot, root-knot nematodes and the peach-potato aphid Myzus persicae (as indicator of Potato virus Y and Potato leaf roll virus). The effects of climate on trends in relative development rates of these pathogens and pests were modelled for each pathogen and pest using a set of quantitative parameters, which included specific temperature and moisture requirements for population growth, compiled from literature. Results showed that the cumulative relative development rate (cRDR) of soft rot and blackleg, root-knot nematodes and M. persicae will increase over the 90-year period in the areas under consideration. The cRDR of early blight and brown spot is likely to increase in the wet winter and wet summer crops of the Sandveld and Eastern Free State, respectively, but remains unchanged in the dry summer and dry winter crops of the Sandveld and Limpopo, respectively. Climate change will decrease the cRDR of late blight in all of the cropping systems modelled, except in the wet winter crop of the Sandveld. These results help to set priorities in research and breeding, specifically in relation to management strategies for diseases and pests.

Effects of potato-cyst nematodes (Globodera pallida) and soil pH on root growth, nutrient uptake and crop growth of potato

Potato-cyst nematodes (Globodera pallida) cause severe yield losses in potato. Plants infected with potato-cyst nematodes generally have reduced concentrations of nitrogen, phosphorus and potassium in the foliage. This study investigated whether reduced growth of nematode-infected potato is caused by nutrient limitation.Experiments in the field and in containers showed that phosphorus concentration correlated best with total crop biomass at early stages of growth. The role of phosphorus in nematode damage was further investigated in the field and in the Wageningen Rhizolab. The experimental field was infested with potato-cyst nematodes and two levels of nematode density were established by fumigation with a nematicide. Prior applications of calcium carbonate resulted in pHKCl levels of 4.8 and 6.1. Two levels of phosphorus fertiliser were applied: either 0 or 225 kg P ha−1. In the Wageningen Rhizolab, soil of both pH levels from the field was used after treatment with 1 MRad gamma irradiation to kill the nematodes. Subsequently, half of the soil was inoculated with cysts to give a nematode density of 30 viable juveniles per gram of soil.In the field, nine weeks after planting, the total crop biomass ranged from 107 g m−2 for the treatment with nematodes at pHKCl 6.1 without phosphorus fertiliser to 289 g m−2 for the fumigated treatment at pHKCl 4.8 with phosphorus fertiliser. The differences in total biomass for the various treatments were explained by differences in foliar phosphorus concentration. Nematodes induced or aggravated P deficiency and reduced total biomass. This was not the only damage mechanism as at high, non-limiting levels of foliar phosphorus concentration, nematodes still reduced total biomass.In the Wageningen Rhizolab, directly after planting, the number of roots visible against minirhizotrons was reduced by nematodes. However, the increase of root number in the nematode treatment continued longer than in the control, until root number was higher than that of the control. The compensary root growth of the nematode treatment was restricted to the top 30 cm and nematodes reduced rooting depth.High soil pH reduced growth, mainly by reducing the availability of phosphate. Both nematodes and high soil pH reduced nutrient uptake per unit root length. Our results lead us to suggest an interaction between nematodes and soil pH, with nematode damage being higher at pHKCl 6.1 than at pHKCl 4.8.

From food safety guidelines to quantified sustainability indicators: A transition to good practice schemes in food production in Europe

Over the last decade and a half various aspects of the sustainability of food production have been evaluated by different groups of stakeholders. National and federal legislators have looked at the types of chemicals allowed and the acceptable maximum residue levels permitted for particular crops and conditions. Commercial firms (in both the processing and retail sectors) have developed private company labels that distinguish them from competitors. Their suppliers have to comply under a‘licence to deliver’. Some organizations that are concerned with environmental issues have developed guidelines. Finally, producer organizations have developed their own labels. The assumption is that farmers who comply have products with added value, which give rise to better opportunities to sell. Some processors source only from growers complying with such schemes. This paper highlights past endeavours, rules and tools to assure food safety, and present initiatives to bring sustainability into the pre-competitive domain. It also identifies future requirements for sustainability indicators and baseline studies, and demonstrates the need to move from indicator values to target values. This approach allows for the quantitative monitoring of environmental safety that will be required for the food industry of the future, just as food safety is now and was in the past.

A Crop Production Ecology (CPE) Approach to Sustainable Production of Biomass for Food, Feed and Fuel

With the rapid increase in demand for agricultural products for food, feed and fuel, concerns are growing about sustainability issues. Can agricultural production meet the needs of increasing numbers of people consuming more animal products and using a larger share of crops as fuel for transport, electricity and heat, while still sustaining the natural resource base? In addition to economic models and learning from statistics and trends, there is a perceived need for decision support tools at global, field and plant levels and for the certification of best practices based on crop production ecology (CPE). This paper illustrates the need for and availability of a generic approach to sustainability principles, criteria, indicators and norms to ensure maximum efficiency in the use of resources such as land, water, chemicals and energy in crop biomass production at various levels of scale. The authors propose a method based on a transportable CPE approach, covering ranges of commodities and environments, to address choices in agricultural production: which crop to promote where, how it should be grown to optimize the efficient use of resources, how to certify the best practices and which crop properties need genetic improvement to make the best use of scarce resources in adverse conditions.

A robust potato model : LINTUL-POTATO-DSS

In 1994, LINTUL-POTATO was published, a comprehensive model of potato development and growth. The mechanistic model simulated early crop processes (emergence and leaf expansion) and light interception until extinction, through leaf layers. Photosynthesis and respiration in a previous crop growth model—SUCROS—were substituted by a temperature-dependent light use efficiency. Leaf senescence at initial crop stages was simulated by allowing a longevity per daily leaf class formed, and crop senescence started when all daily dry matter production was allocated to the tubers, leaving none for the foliage. The model performed well in, e.g., ideotyping studies. For other studies such as benchmarking production environments, agro-ecological zoning, climatic hazards, climate change, and yield gap analysis, the need was felt to develop from the original LINTUL-POTATO, a derivative LINTUL-POTATO-DSS with fewer equations—reducing the potential sources of error in calculations—and fewer parameters. This reduces the number of input parameters as well as the amount of data required that for many reasons are not available or not reliable. In LINTUL-POTATO-DSS calculating potential yields, initial crop development depends on a fixed temperature sum for ground cover development from 0% at emergence to 100%. Light use efficiency is temperature dependent. Dry matter distribution to the tubers starts at tuber initiation and linearly increases up to a fixed harvest index which is reached at crop end. Crop end is input of the model: it is assumed that the crop cycle determined by maturity matches the length of the available frost-free and or heat-free cropping season. LINTUL-POTATO-DSS includes novel calculations to explore tuber quality characteristics such as tuber size distribution and dry matter concentration depending on crop environment and management.

Foliar calcium concentration of potato and its relation to genotype lateness and tolerance of cyst nematodes

In field trials during three years respectively 18, 22 and 57 potato genotypes were grown on soils moderately or heavily infested with potato cyst nematodes (Globodera pallida) after soils were fumigated or not. Nematode infection increased leaf calcium contents but genotypes that were relatively tolerant of potato cyst nematodes (Globodera pallida) had lower leaf calcium concentrations on a particular sampling date. Tolerance of potato cyst nematodes was closely linked to genotype lateness and may be related to tolerance of drought. When using the method in plant breeding and screening for genotypes with tolerance, plants may be planted in infected or in uninfected soils, without influencing the outcome. The relationship between tolerance and calcium contents was clearest when sampling took place towards the end of the growing season when the variability was at it highest with a good distinction between newly formed leaves in late maturing genotypes and aged leaves in early maturing cultivars.

Carbon footprinting of potato (Solanum tuberosum L.) production systems in Zimbabwe

Agriculture contributes significantly to the global greenhouse gas (GHG) emissions. Farmers need to fine-tune agricultural practices to balance the trade-offs between increasing productivity in order to feed a growing population and lowering GHG emissions to mitigate climate change and its impact on agriculture. We conducted a survey on the major cultural practices in four potato production systems in Zimbabwe, namely large-scale commercial, communal area, A1 and A2 resettlement production systems. The resettlement production systems were formed from the radical Fast Track Land Reform Programme initiated in 2000, which changed the landscape of commercial agriculture in Zimbabwe. We used survey data as an input into the ‘Cool Farm Tool – Potato’ model. The model calculates the contributions of various production operations to total GHG emission. Experienced growers were targeted. The average carbon footprint calculated was 251 kg CO2 eq./t potato harvested, ranging from 216 kg CO2 eq./t to 286 kg CO2 eq./t in the communal area and A2 resettlement production systems, respectively. The major drivers of the GHG emissions were fertilizer production and soil-related field emissions, which together accounted for on average 56% of the total emissions across all production systems. Although mitigation options were not assessed, the model outputs the factors/farm operations and their respective emission estimates allowing growers to choose the inputs and operations to reduce their carbon footprint. Opportunities for benchmarking as an incentive to improve performance exist given the large variation in GHG emission between individual growers.

Analysis of the potato (Solanum tuberosum L.) value chain in Zimbabwe

The performance of the Irish potato sector in Zimbabwe is not well understood. Using value chain analysis, this article evaluated the potato industry using quantitative data gathered from stakeholders using structured questionnaires, field observations, local knowledge and expert consultation. About 65% of potato production is processed as French fries and less than 35% for household fresh consumption. Average fresh potato household per capita consumption was 34 kg per year, while the total per capita consumption was 9 kg per year. Gross profit estimated at each linkage was at least 13%. Major factors impacting on the value chain performance relate to high production costs, low yields and a lack of farmer training. Potato marketing is also hampered by the poor road network in the country. The research recommends a lowering of production costs, supplying high yielding cultivars, providing credit facilities, guaranteed land ownership and improving the country’s road network.

Netherlands public private partnerships aimed at Co-innovation in the potato value chain in emerging markets

Abstract Since 2013 the Netherlands Ministries of Economic and Foreign Affairs has been involved in private companies in research and development (R&D) in developing countries. This in a policy going “from aid to trade”. Especially in upcoming markets, R&D is carried out through Public Private Partnerships. Such partnerships not only include R&D organizations in the two countries but specifically also include businesses in both countries. This was to assure a logical flow of material and knowledge by all parties involved. Half of an R&D project is funded by the ministry and the rest is covered by a consortium of companies that contribute in kind and in cash. The policy is aimed at stimulating business development in developing countries and the Netherlands through cooperation and joint R&D. The paper explains how eleven consortia around potato business opportunities were formed, their R&D need was elicited and R&D projects formulated in the Asian countries China, India, Indonesia, Vietnam, Bangladesh and Myanmar, and Ethiopia and Kenya in Africa. In common are fact finding and descriptions of cropping systems, yield gap analysis and value chains in each country. Emphases differ with China looking for an integrated system of field operations, India for optimization of storage and processing, Indonesia to reduce pesticide and nutrient inputs, Vietnam for widening the varietal base, Bangladesh for combating late blight, Myanmar for cultural practices that lead to increased yield, Ethiopia where a potato processing unit is being established and Kenya importing seed potato from the Netherlands. Some content information is given as examples to illustrate the approach and some preliminary conclusion are discussed.

A Quantitative Framework for Evaluating the Sustainability of Irish Potato Cropping Systems after the Landmark Agrarian Reform in Zimbabwe

Frameworks to evaluate the sustainability of cropping systems in developing countries are scarce. This study proposes a framework to select easily quantifiable indicators that can be used to assess and communicate the sustainability of cropping systems in developing countries. The widely accepted social, economic and environmental dimensions of sustainability were covered using predefined criteria from which the indicators were then drawn. An initial list of indicators was established based on literature review and expert opinion, and through filtering reduced to 16 core indicators. Using the case of Irish potato-based cropping systems, a grower survey was conducted to collect data on production practices in four different cropping systems. The survey data were then used to calculate the sustainability indicators expressed as resource use efficiencies based on actual potato yields. The survey data also served as input into the Cool Farm Tool – Potato model to estimate greenhouse gas emissions from farm operations involved in potato production. With the help of local agricultural extension officers, focus group discussions were held with farmers of each production system to decide on sustainable and unsustainable indicator threshold levels. The participatory nature of the framework involving farmers and local extension officers secured buy-in from key stakeholders important for operationalization, monitoring and evaluation.