Soil Improvement
Soil structure has been shown to influence a wide variety of soil processes, such as water and chemical transport, soil aeration, soil erosion, seedling emergence and root penetration in the soil.
Regular annual applications of Gypsum can improve soil structural issues such as soil compaction, contoured land, soil salinity, acid sub soils as well as reducing nutrient loss to nearby waterways. It helps reduce wind and water erosion on cultivated land. A well aerated soil with good organic matter will reduce the severity and incidence of Phytophthora root infections.
The calcium in gypsum also increases the activity of soil organisms. Soil microbes break down dead plant material and other organic matter. This process produces organic ‘glues’ that bind soil particles together and stabilise soil structure. Decomposed organic material is also bound to clays at a molecular level via calcium. Earthworm activity is increased by calcium, and this brings with it many benefits including increased aeration, increased mixing of organic matter, and macropore formation.
To obtain significant improvements regular applications of gypsum every year or biennially, from anecdotal evidence application rates on clay soils of up to 1,000-3,000 kg/ha of gypsum may be required.
Soil Compaction
Soil compaction is a common consequence of the intensive management systems that are employed in modern agri/horticulture. It changes the distribution of pore sizes, increasing the number of small pores. Damage to the soil structure and compaction issues can be caused by farm machinery on wet, clay soils and grazing animals in wet conditions. As a result soil stay soft and wetter for longer which further increases its susceptibility to more soil damage. Damaged soil suffers reduced water infiltration rates, reduced water-holding capacity and reduced root-zone depth.
Soil compaction below the cultivation depth and subsoil acidity can badly affect the depth of a plants' root zone. A visual inspection of the soil profile will identify if there is compaction below the cultivation depth.
While topsoil compaction is improved by cultivation, subsoil compaction is worsened by it. Deep ripping is effective to break up the pan which will facilitate the downward movement of calcium into the subsoil. However, if the underlying causes of subsoil compaction are not addressed, deep ripping will be only a short-term remedy.
Gypsum helps to reduce compaction in subsoil layers, and in ‘cultivation pans’ as the relatively high solubility of gypsum allows it to move down through the soil profile. Apply gypsum during spring and autumn when soil moisture content is high to aid with dispersal into the soil.
Contoured Land
New vineyard and orchard developments are often ‘contoured’ to remove the worst of the topographical irregularities. These soils are often subject to deep ripping and surface cultivation, especially where subsoil has been exposed by topsoil removal. This results in soil being particularly low in organic matter and nutrients, poor drainage can also be a problem.
Applications of gypsum can assist to remedy many adverse soil conditions. Gypsum encourages soil structure improvements with better retention of organic matter as well as aiding the movement of water through the soil profile. Gypsum also helps to reduce wind and water erosion that can be a problem in freshly prepared and exposed soils during the early years of vineyard and orchard establishment. Gypsum can also help with compaction problems.Apply gypsum during spring and autumn when soil moisture content is high to aid with dispersal into the soil.
Soil Salinity Issues
Acid subsoils have high levels of exchangeable aluminium and sodium which limits root growth. High sodium content causes loss of soil structure, reduction in pore spaces and may increase soil pH in severe situations. Often a layer of compaction (a hard pan) exists, preventing the crop accessing water deep in the soil profile.
Soil acidification is an inevitable consequence of intensive cropping and the forms of nitrogen fertiliser used.
The sulphate ions in gypsum binds with aluminium as well as sodium and removes it from the subsoil. The calcium in gypsum increases precipitation of phosphate as calcium phosphate, preventing it leaching into waterways.
Clay Soils
Clay textured soils tend to swell when wet, and to shrink when they dry. This causes large cracks to appear at the surface.Clay soils with a high level of magnesium will have reduced air spaces and heavy soil structure. After rain the soil is sticky and difficult to manage, making tractor work difficult.
Gypsum reduces the amount of shrink and swell by moderating change in water status. The amount of cracking is therefore reduced. The sulphate ions in gypsum binds with excess magnesium in the soil and removes it from the soil profile.
Nutrient Loss to Waterways
The main nutrients, nitrogen and phosphorus, are involved in loss from soils to waterways. New Zealand soils are well known to be sulphur deficient. Superphosphate applications raises the concentration of sulphur and phosphorus in the soil, increasing the risk of phosphorus runoff into nearby waterways, reducing waterway quality through eutrophication.
Nitrogen loss to waterways is due to high application rates of nitrogen fertiliser, with plants unable to take up all the fertiliser immediately resulting in excess levels of nitrogen in the soil. Loss to waterways can occur during high rainfall events.
Gypsum, applied to soil improves water infiltration rates and soil aggregate stability, reducing surface water runoff as well as phosphorus leaching due to calcium in gypsum binding with phosphorus.
Gypsum Product Range
Claybreaker™ Finely ground gypsum for use on clay soils and home garden. Pack sizes include 8kg and 25Kg bags.
Soil Life® Finely ground gypsum for use in horticultural and agricultural situations. Pack sizes include 25 Kg bags and 1000 Kg sling bags.
Natural Screened Gypsum Screened gypsum for use in horticultural and agricultural situations. Available in 25Kg bags, 1000Kg singbags, bulk truck and trailer deliveries.
Where to Buy Gypsum
View distributors here.