When growing roses on soil one experiences many challenges like salinity which occurs through natural processes like weathering or human-induced processes. Weathering breaks down rocks and release soluble salts of various types, mainly chlorides of sodium, calcium and magnesium, and to a lesser extent, sulphates and carbonates. Sodium chloride is the most soluble salt which causes accumulation of dissolved salts in the soil water to an extent that inhibits plant growth resulting to stunted growth. Irrigating with poor quality water usually does not have an immediate negative effect on plant growth. Â Rather the sodium builds up in the soil and results in a long term hazard eventually reducing soil productivity and killing the plants.
A saline soil has high concentration of soluble salts that affect plant growth. Sodium is associated with high salinity water. Salt concentration in soil is measured in terms of its electrical conductivity. Normal EC for optimal cultivation of roses should be between 1.5-1.8.
Salinity affects almost all aspects of plant development including: germination, vegetative growth and reproductive development. It imposes ion toxicity, osmotic stress, nutrient (N, Ca, K, P, Fe, Zn) deficiency and oxidative stress on plants, limiting water uptake from soil. Soil salinity significantly reduces plant phosphorus (P) uptake because phosphate ions precipitate with Ca ions. Some elements, such as sodium, chlorine, and boron, have specific toxic effects on plants. Excessive accumulation of sodium in cell walls leads to osmotic stress and cell death. Because many salts are also plant nutrients, high salt levels in the soil can upset the nutrient balance in the plant or interfere with the uptake of some nutrients. Salinity affects photosynthesis mainly through a reduction in leaf surface area, chlorophyll content and stomatal conductance hence affecting the quality and lowers production of roses.
Sodium Adsorption Ratio (SAR)
This parameter is calculated from the sodium, calcium and magnesium concentrations in the water. Â Calcium and magnesium counteract the negative effect of sodium in the water and reduce the SAR value. Sodium causes the soil pores to close up and make wetting the soil and water infiltration difficult causing permeability problems.
Low salinity water with high sodium has lower permeability into soils, than high EC water. Â Water with a higher EC has less surface tension and will infiltrate the soils more easily in water with a high SAR. Â The surface tension and infiltration can also be improved by adding wetting agents and humic acids.
Control
- Salinization can be restricted by leaching of salt from root zone and improve irrigation practices by using quality water.
- The SAR can be manipulated by adding calcium and magnesium to the water. Â EC can be increased, within reason, by adding fertilizers.
- Drenching SILVEDO GOLD at 5L/ Ha is done to replace the sodium ion with calcium and then the replaced sodium can easily be leached out of the root zone using irrigation water. Apart from correcting soil salinity silvedo gold also corrects calcium deficiencies and improves cell structure.
SILVEDO GOLD® is an organic liquid complex of calcium, for irrigation applications in different fertigation systems. It is an effective corrector of soils and water salinity, sodicity and other detrimental ions and improving soil structures with compaction problems thus enhancing soil aeration and drainage.
- Drench Humipower 4kg/Ha or Humigreen Extra 4L/Ha to promote electrochemical balance as either a donor or receptor, making minerals and other nutrients assimilable by plants.
HUMIPOWER® is a water soluble soil amendment and blend that contains potassium, Iron EDDHA, humates and fulvic acid in granular form. It is used in agricultural, horticultural and field crops, landscaping lawns, pot plants as well as gardening. It is used both in the soil as an amendment and as fertilizer blend and supplies plants with organic matter that is readily available, easy to use and cost effective.
