How to Manage Crops in Heavy Rainfall

Too much rain is bad for crops. Apart from the obvious loss of crops being washed away by floodwaters, waterlogged soils affect crops negatively by reducing crop performance and productivity.

Too much water in soil means that the soil pores are filled with water, thus replacing Oxygen which is necessary for root health, as well as other microbes in soil. Basically the soil drowns. Roots can no longer feed and grow properly, leading to poor crop performance.

Aerobic microbes cannot survive in drowned soils. This leaves the anaerobic microbes to dominate. Whereas aerobic microbes help to avail minerals from organic matter to the plants, anaerobic microbes are just the opposite: can produce toxic gases from the minerals (eg Hydrogen sulphide), and many cause diseases. This can render the crops sickly and eventually dead.

When conditions are too wet, certain minerals are leached through percolation resulting in a soil mineral imbalance. This renders the minerals unavailable to the crop, and can increase soil acidity over time. These Highly leachable minerals include:

  • Nitrogen; (necessary for tissue growth and photosynthesis). Crops become stunted, appear pale and yellow.
  • Boron; (for successful pollination and fruit production). Crop will be stunted with flowers / fruit abortion.
  • Sulphur (for crop growth). Crops will look emaciated and discoloured.
  • Potassium (for fighting disease, flower and fruit production, and water use in metabolism) crops will look withered and discoloured, with poor fruits.

In order to minimize the effects of too much rain on your crops, do the following:

  1. Grow on raised beds: plant on raised beds to allow water to drain out the root zones.
  2. Surface draining: digging of trenches which drain the water away from crops.
  3. Nutrient management:
  4. Apply manure before planting. Manure increases the concentration of some minerals (Zn, Fe, Zn) and improves soil structure (aeration).
  5. Use Slow release fertilisers during planting. This helps to slow down the rate of leaching.
  6. Replenish the lost minerals through foliar application. Apply HARMONY which increases crop uptake of minerals due to Fulvic acid, and replenishes Nitrogen through the foliage when roots may be already damaged.
  7. Control harmful soil pathogens to reduce risk of disease. Apply RODAZIM during planting and soon after germination.

To rehabilitate chronically waterlogged soils, practice Bio-drainage: use of deep rooted crops with high water consumption, to pump out the water through transpiration. Example: fast growing tree species like eucalyptus.