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Food SFood Securityecurity
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Food – Water – Life


Our farmers, who balance in their green fingers the delicate scales of food security and social equity, also face the commercial pressure of international
markets and shifts in consumption patterns. Yet South Africa’s commercial agriculture sector is increasingly viewed by upstream and downstream industries. The government especially views the sector as an overly  thirsty and at times thrifty water user.

The term ‘farm water’ refers to water used to irrigate crops, leach harmful salts from fields, and to manage the environment. Water Bombs For Farmers
Recently, agriculture’s 62% guaranteed supply of our country’s surface water was fingered personally by the Environment and Water Affairs Ministry for nipping mining and industry growth in the bud, with a sweeping wag at using excess water as a private sector trading stock.

The National Water Policy Review, now in circulation, aims to address legislative gaps in the sector, and arguably seeks nationalisation of temporary and permanent water trading of any nature. With 98% of this “basic human right” resource allocated – and a huge rural access backlog, the logic is clear.

Interestingly, however, the Food and Agriculture Organisation (FAO) cites a greater reliance on farmer-owned and -operated irrigation among its key water-saving measures.

Food Security

Loss of water from a crop field during the growing season results primarily from evaporation from the soil surface, and transpiration through the plant leaves. These processes are termed “evapotranspiration” and commonly abbreviated “ET”

Water – Tricky Flow Models

While the world population grew from 2.5 billion in 1950 to 7 billion, the irrigated area doubled and water withdrawals tripled. When scarce water is under human control via irrigation systems, and irrigation gets a bad rap, it’s a sign to investigate the problems and the potential for improved efficiency. To review irrigation practices, farmers must test cost and time overruns; poor management; the non-realization of full, planned benefits; adverse environmental
and health impacts; and the exacerbation of inequities in the existing social and economic distribution of assets.

Food Security

Top: Variation of the temperature stress coefficient (Ks) for cold (left) and heat stresses (right) on pollination Above: Schematic representation of the crop response to water stress, as simulated by AquaCrop, with indication (dotted arrows) of the processes (a to e) affected by water stress (adjusted from Raes et al., 2009).

Globally since the mid-70s, ballooning construction costs, falling wheat and rice prices, the environmental and social cost revolution and poor irrigation performance at farm level have combined to shrink the necessary growth in the coverage of irrigated land. Just as ageing irrigation projects have produced gradually declining yields, modernization of existing irrigation projects is becoming increasingly expensive. Old projects that were designed for mnocropping
also need to be redesigned to permit crop diversity, increase yields, conserve water and reduce environmental hazards.

Modernization involves canal lining, improved hydraulic control structures, better land development and appropriate irrigation techniques. Leading The Farm Horse To Water Economic water scarcity means a lack of infrastructure, with people often having to fetch water from rivers for domestic and agricultural use.

The resulting over-development of hydraulic infrastructure for irrigation often leads to environmental degradation and declining groundwater. Around 1.3-million hectares of South African farmland is under irrigation. The ideal is to apply the right amount of water, at the correct application rate and uniformly to a field, at the right time, with the least amount of non-beneficial water consumption (losses), and as economically as possible, says the Agricultural Research Council. The agriculture sector faces a complex challenge: producing more food of better quality while using less water per unit of output; providing rural peoplem with resources and opportunities to live a healthy and productive life; applying clean technologies that ensure environmental sustainability; and contributing in productively to the economy.

Fluid Institutional Guides

With agriculture in constant evolution, irrigation needs to adapt to new, more stringent requirements. The supply of water within large irrigated systems needs to be much more reliable and flexible than in the past. Sound simple? The South African Framework for Improved Efficiency of Irrigation Water Use views water-management infrastructure from four vantage points: the water source, bulk conveyance system, irrigation scheme and irrigation farm.

The South African Irrigation Institute represents 450 designers, engineers, soil scientists, crop experts, economists and irrigation farmers, as well as 50 manufacturers and suppliers of irrigation equipment, applying their minds to this task. The FAO’s approach to irrigation and drainage, widely used today, is based on the relative yield loss of any crop, whether it be either herbaceous or woody species, to the relative reduction of water consumption, i.e. evapotranspiration, specific for any given crop and condition. Responding to the evolutionary idea of synthetic water production needs over the last three decades, the FAO created a unique crop simulation model, called AquaCrop.

This simulation model calculates the crop biomass, based on the amount of water transpired, and the crop yield as the proportion of biomass that goes
into the harvestable parts.

Cannot Control What Can’t Be Measured

South African commercial farmers, and their institutional guides, would do well to invest more time and money into water measuring equipment. This will allow them to correctly measure and protect the precious water resources allocated to them, while at the same time reducing associated electricity costs. By combining the FAO’s AquaCrop model with a trusty water metering system, farmers can better motivate the retention of their water allocations to water authorities. In turn, water authorities will have more reliable data to base their vital decisions on.

The financial returns of an irrigator are strongly correlated with the volume and pattern of irrigation water application – saving water and electricity costs, says the Water Research Commission (WRC). The Department of Water Affairs (DWA) will also publish new regulations for river, irrigation scheme and
farm water measurement, ensuring stricter enforcement of water metering.

Whereto From Here

To assist farmers and policy-makers, the WRC published a report for sustainable on-farm and on-scheme irrigation water measurement with the Department of Agriculture, Forestry & Fisheries, guiding the process to effectively implement water measurement at river, irrigation scheme and
farm level in South Africa.

 

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