Applying Gypsum - Gypsum New Zealand

By: Gypsum  06-Dec-2011
Keywords: Fertilisers, Gypsum Application

Gypsum mixes well with other dry fertilisers - particularly granulated forms. Gypsum is also useful as a carrier to assist in the uniform application of small quantities of zinc, manganese, boron and the other trace elements. Conveniently, 1 kg of gypsum has a volume of approximately 1 litre (1 tonne has a volume of 1 m


). Quick inter-conversion between mass and volume simplifies accurate measurement.


Most production fruit crops require between 250 and 500 kg/ha of calcium each year. A substantial part of this can be supplied in the form of gypsum with other calcium-containing fertilisers accounting for the balance. Commonly, nitrate is applied in the form of calcium ammonium nitrate (containing 27% of nitrogen and 8% of calcium) at the rate of around 300 kg/ha. This supplies only 24 kg/ha of calcium so that most of the required calcium can be supplied in the form of gypsum (300 kg/ha of calcium requires 1,200 kg/ha of gypsum).


Most horticultural crops need about 120 kg/ha of sulphur annually. About one third of this will come from the organic sulphur cycle within the soil, one third from a base dressing of gypsum (40 kg/ha of sulphur requires 220 kg/ha of gypsum) and the balance from other sulphur containing fertilisers.

Soil Structure

To obtain significant improvements in the structure of clay soils requires much higher rates of gypsum application (2,000-4,000 kg/ha of gypsum).


Gypsum relies upon rainfall to solubilise it and so move it into the soil profile where it has its effect, it is therefore best applied in early spring or after harvest when rainfall can do its work. It can, however, be applied at any time because gypsum does not damage plant tissues - even at high application rates.

Calcium transport into fruit occurs mostly during spring. Where gypsum is being used to remedy a soil calcium deficiency, it is best to apply it well before bloom to ensure that the calcium reaches the feeder roots in good time.

Ground gypsum is quite fine and even the pulverised product contains a proportion of fine material. It should, therefore, be applied only in calm or at the most 'light breeze' (1-2 knots) conditions. Otherwise, substantial amounts of the product will be blown away from the target area and may cause offence to the neighbours.

Keywords: Fertilisers, Gypsum Application

Other products and services from Gypsum


Product Info - Gypsum New Zealand

To meet differing market requirements, Winstone Wallboards produce two, chemically identical, products - Soil Life a fine ground form and Gypsum Natural a coarser pulverised form. Its special benefits are that horticultural gypsum is fast acting and pH neutral (contrasting with other calcium fertilisers that are slower and either raise or lower soil pH).


Waterborne Application - Gypsum New Zealand

Their physical condition is degraded by tillage, the use of machinery etc; their chemical condition is degraded by the crop's removal of minerals, by leaching etc; and their moisture content is depleted by transpiration - plants remove water from the soil at a rate proportional to their growth.


Subsoil Compaction Affects Wheat / Barley Yield

Soil acidification is an inevitable consequence of intensive cropping with silage crops having greater acidifying effects than grain crops due to the removal of the basic cations contained in the straw. Normal practice is to apply lime and to cultivate this into the topsoil to achieve appropriate pH and calcium levels based on annual soil tests made prior to planting.


Subsoil Compaction Affects Maize Yield

While management of just the 0-20 cm topsoil layer is sufficient to meet the crop's mineral nutrient requirements, to provide it with sufficient water in summer requires either regular irrigation or root zone access to water contained in a much deeper soil profile - roughly from 0-100 cm.


Effect of Dairying on Pasture Soils

The pasture growth reduction can be offset to some extent by increased fertiliser usage but this tends to decrease soil pH and to increase nutrient loss so they are not remedial in their effects - more of a 'band-aid' approach. In recent years we have seen good growth in the New Zealand dairy industry associated with a rise in dairy cow numbers along with higher stocking rates and increased use of nitrogen fertilisers.