Viticultural Info

SA Composters Viticultural Info

USE OF COMPOST AND MULCH IN VITICULTURE

Composted mulch can be used to increase productivity and sustainability of viticulture production. There are a few benefits of using composted mulch in viticulture farms:

1. Reduce risk of crop failure

Application of composted mulch can reduce soil temperature by up to 20C, which increases soil moisture levels, reduces plant stress, and reduces risk of crop failure.

Mulching reduces evaporation from the soil surface, increases water conservation and resistance to drought, particularly in non-irrigated areas, and reduces the risk of crop failure.

2. Increased revenue

Composted mulches have the potential to increase grape yield up to 27% depending upon grape variety, environmental conditions and farm management practices.

Composted mulches can potentially improve grape fruit quality.

3. Reduce farm management costs

Composted mulches reduce evaporation from the soil surface, increase water conservation, and therefore result in more efficient water use. This could reduce irrigation water requirement of grapevines by 10% or more (depending upon environmental conditions, irrigation systems and farm management practices).

Composted mulches slowly release essential macro and micronutrients for plant growth. This reduces the use of mineral fertilisers by 30% or more and makes mineral fertiliser programs more effective.

Composted mulches reduce weed growth between 60-100% and decrease the requirements for herbicides, thereby reducing farm production costs.

4. Increased farm capital value

Mulching reduces the direct impact of wind and rain from dislodging the topsoil from the landscape, and reduces erosion by up to 100%. This can prevent land degradation and improve soil health and land productivity.

Composted mulches add organic matter to the soil. This improves soil aggregation and soil structure; reduces surface sealing, increases water infiltration, and water holding capacity of the soil, thereby improving the overall soil health and land productivity.

5. Improved environmental performance

Improved ecological integrity and biodiversity - Reduced erosion reduces sediment transport to rivers and improves water quality; reduced irrigation water usage allows for increased environmental flows in rivers and improved water quality. Both lead to increased ecological integrity and biodiversity of water resources.  Improved soil health (increased organic matter, improved soil structure, reduced soil temperature fluctuations) also result in increased biological activity, which may also be considered as an increase in ecological integrity and biodiversity.

Reduced resource depletion - Reduction in soil structure decline, reduction in topsoil loss, reduction in soil organic carbon loss and reduced use of agricultural chemicals and fertilisers leads to reduced resource depletion.

Reduced global warming potential - Reduced use of agricultural chemicals and fertilisers reduces production of fertilisers and agricultural chemicals leading to reduced greenhouse gas emissions. Sequestration of carbon in the soil acts as a carbon sink also reducing global warming potential.

Reduced soil erosion - Improvement in soil physical properties leads to reduced soil erosion.

Reduced human and ecotoxicity -Reduced use of agricultural chemicals and fertilisers reduces production of fertilisers and agricultural chemicals leading to reduced release of chemicals that can be toxic to humans and environment.

A 10 cm thick layer of composted mulch application to a viticulture farm would offer the following benefits:

  • Can prevent soil loss of up to 17.5 t/ha/yr;
  • Savings in irrigation water of about 1 mega litre/ha/yr;
  • Savings of 72-108 kg nitrogen, 120-180 kg phosphorus and 90-135 kg of potassium fertilisers per hectare over 3-5 years;
  • Can replace 2-6 L of herbicide glyphosate for weed suppression;
  • Can improve grape yield up to 27% per hectare; and
  • Can increase soil carbon up to 7 t/ha after 100 years (improving soil structure in the shorter term, and sequestering carbon in the soil as a greenhouse sink over a much longer duration).

Application guide for using composted mulch in viticulture:

Compost products can vary significantly in terms of nutrient content. Application of composted mulches should seek to match the nutrient requirements of the crop with those supplied from the compost, as this will maximise the reduction of additional fertiliser required. This requires balancing the selection of product type with application rate and cost to also deliver desirable outcomes such as weed suppression and moisture retention.

Where possible timing of composted mulch application should be similar to the regular fertiliser application schedule to avoid excessive nutrient application at the incorrect time.

Coarser composted mulches are applied on the soil surface around the grapevines after planting. The mulch should not be in direct contact with vine stems as this can result in stem rot.

Composted mulches are ideally applied to established grapevines prior to bud burst to allow for machinery access between rows without risk.

Specific requirements and performance priorities vary with soil type, climate and a host of other variables. Your local compost producers are likely be the best source of expertise, and can help to identify the appropriate composted mulch product for your situation. Issues to consider include: your performance priorities, nutrient provision and recommended application rate, product quality and quality assurance of the manufacturer.

Fertilizing vines with Fishers Creek Rock Dust

Fishers Creek Rock Dust (click here for further information about FCRD) is a natural crushed volcanic rock fertilizer produced in far north Queensland. The otherwise untreated mineralized rock dust has the potential to deliver plant nutrients – namely potassium (K) and phosphorous (P). With 500g/m2 the maximum nutrient applied would be 16kg/ha P and 11kg/ha K – deficits in average vineyard requirements of 4 and 9 kg/ha of P and K respectively. Nutrient availability will depend on soil, cultural and climatic conditions and is difficult to predict without soil-specific testing. P availability in soils with clay content may be improved; research undertaken in Queensland has demonstrated the ability of the high silicon content of the FCRD to block P sorption sites allowing greater plant available P.

Compost and FCRD blends have the potential to more than satisfy the nutrient requirements of the average vineyard. With a depth of 25mm compost (33m3/ha) and 500g/m2 (667kg/ha) FCRD, the plant available nitrogen (N) phosphorous and potassium may be around 56, 30 and 195kg/ha respectively, giving excess amounts of 16, 10 and 175kg/ha. This may be a significant benefit where synthetic fertilizers are not used or minimized.  Low application rates of compost may be more beneficial for growers; the penalty in applying enough compost to satisfy N and P requirements is an excess of K. Wine grape producers are sensitive to excess potassium due to the potential effect of potassium in reducing wine acidity and negatively impacting the keeping quality of the wine. Lower rates of compost will allow lower inputs of K and growers will be able to manage N and P levels independently of potassium.

The table provided (click here to view table) specifies some of the differences between compost and mulch products for use in viticulture, with notes on method of application. Conclusions are generally as follows:

(A) Compost consisting of finer particle sizes is ideal for incorporation into soil and for supply of nutrients, soil structure improvement, and planting of new vines

(B) Mulch consisting of larger particle sizes (or a blend of large and small particles) is best used on the soil surface, where it is ideal for weed control in young and established vines, and reduces both rapid infiltration and reduced water loss from the soil by evaporation.

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