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water management

Whether natural or cultivated, healthy ecosystems rely primarily on water. Therefore, one of the key areas of Natuurboerdery® is the management of water, which is the main constraint for farming operations in South Africa.

The whole farming operation already converted to drip irrigation in 1983-84. Contouring and run-off control was gradually developed to a standard where soil erosion and stream eutrophication through leading was effectively eliminated. This discipline proved its worth in the massive floods of 2000, when most dams were destroyed, but no cultivated lands were washed away.

Scientific monitoring of rainfall and soil moisture led to steady improvement of irrigation practices, including the introduction of the Motec system. The use of compost contributed greatly to better water penetration and retention.

Various trials to limit evaporation were conducted. A variety of plastic mulch covers on tomatoes were tested. Although successful for limiting weeds and evaporation, these proved both too expensive and environmentally unacceptable: the plastic was impossible to sanitate from resting fields, and caused problems with cattle grazing there.

We realise our responsibility to manage water and great emphasis is placed on all facets of water provision. This includes: 

  • Safety of dams
  • Borehole monitoring
  • Pipelines
  • Water drainage control planning

Drainage of water and nutrients is curtailed in this way by using the latest automated irrigation technology. We use water efficiently and irrigation scheduling is based on what the plants need, as well as climatic requirements.

Organic mulch proved too expensive on the short lived tomatoes for the benefits it provided, but was used extensively on avocados since 2004. A mix of wood chips, cattle dung and EM is applied.

Description.

A major water saving was achieved with tomatoes in net houses. Here plastic mulch was absolutely indicated and combined with the reduced evapo-transportation through wind, resulted in an average reduction of 25% of irrigation water per tonne tomatoes produced. Various experiments with minimum cultivation and ground cover plants, were conducted, also in consultation with our engineers to find suitable machines. None of the efforts were successful because the absolutely essential ridging had to be abandoned.

While our above ground available water was eventually optimally harvested through a system of sophisticated dams, pumps and pipelines, the more expensive underground sources were mainly used as supplement and reserves in times of drought. Recently we commissioned a survey of our ground water reservoirs (complete with replenishment rates, water quality and sustainable utilisation) from the company AGES.

This enables us to optimally manage our whole natural water resource on a sustainable basis, with a GIS system reflecting every one of several hundred boreholes together with its attributes.

By diligent nature conservation of our stream catchment areas we have managed to maintain the stream flow on our farms. Since 2001 there is an ongoing effort to eradicate invader Seligna and Wattle in our mountains, which has resulted in notable stream flow improvement.

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