Soil Water Conservation and EcoCover Mulch Mats

Definition of Water Conservation

"The careful preservation and protection by way of planned management of water as a natural resource to prevent exploitation, destruction or neglect."

Water conservation is of vital concern globally and will be of even greater importance in the future. By 2020 it is estimated the world's population will be 7.5 billion. Predictions have been made that unless it stabilizes at between 8.5b and 10b by 2050, all available arable land will be dedicated to producing food of plant origin. This in turn will bring enormous pressure on the world's available water of which only 70% is available for use and of that 70%, 65% is used in agriculture, 22% by industry and only 7% remains for households (Lappe, 1999). Population pressure on land resources will increase dramatically in the near future unless agricultural productivity (yield per unit area) grows concomitantly with population. New technology will be needed to increase crop productivity in a sustainable fashion, without converting more natural areas to cropland. EcoCover is representative of this new technology.

Read Drought as the New Normal.

EcoCover mulch mat conserves soil moisture by reducing the evaporation of water from the soil by wind and sun. Air movement (wind velocity) is reduced to nil at the soil surface. Soil moisture moves by capillary action to the surface and considerable losses may occur if the soil surface is not covered by a mulch.^{11, 12}

Mulch acts as a vapor barrier that reduces the frequency that soil moisture must be replenished and also reduces the chance of water stress on plants. Since evaporation is reduced, soil moisture is likely to be higher in a mulched soil.^{12, 13} EcoCover is particularly effective when used in conjunction with drip irrigation. Traditional spray irrigation loses about a third of the water to evaporation and winds.²⁰

Mulching is an important practice for establishing plantings as it helps to conserve moisture in the root ball of the new plant until it establishes roots in the adjacent landscape.¹³

EcoCover mulch mat will shade the soil surface and provide a physical barrier, reducing weed growth and shield the soil and plant roots from the effects of solar radiation and temperature extremes.^{12, 13, 14, 36}

The degree of soil temperature modification is primarily determined by both the optical and thermal properties of the mulch. The most effective mulch mats act as a soil insulator that maintains a more uniform soil temperature, reducing the difference between day and night temperatures (diurnal) and keeps the soil cooler in summer and warmer in winter. Microorganism activity in the soil is more constant under mulched soil when compared to bare soil due to fewer extremes in temperature.¹¹ Dark mulch can however absorb more solar radiation and may increase soil surface temperature. Transparent plastic mulches can increase soil temperature via a greenhouse effect.^{4, 12}

EcoCover reduces evaporation and can prevent up to 75% water (10-50% is more common depending on the thickness and type of mulch15) loss due to evaporation.¹⁰ EcoCover slows evaporation in even the hottest conditions reducing the need for watering. Increased moisture retention means less cracking in the soil and vital air and water movement through the soil is also improved. Moisture retention results in better temperature stability in hot and cold conditions, reducing the risk of stress to new plantings and frost damage during winter.

Pooling and ponding is reduced due to the transfer of water. This is particularly important with crops such as strawberries for example that can suffer from excess water stress.

Integrated pest management, nitrogen fixation, soil conservation, and the efficient use of water are important components of new crop production methods.

The application of the really effective mulches can conserve soil moisture and provide earthworms with protection from sudden changes in temperature. It can also provide them with an additional food source. Consequently earthworm survival is usually favored where mulches are applied.¹⁶

The use of mulches for tree and shrub planting has become increasingly popular in recent years.¹⁷ Competition for moisture in the soil makes the elimination of weeds essential in the planting of tree seedlings for forestry particularly in drought prone areas where the water conservation properties of the mulch can substantially reduce early mortality in seedling.¹⁸ In drought prone areas of New Zealand it has been recommended that new plantings do not take place unless mulch is used.¹⁸

In Queensland, Australia, some property sales during 1999 demonstrated that water license values represented around 75% of the total value of properties being sold. Water is a valuable and increasingly scarce resource.¹⁹ The projected growth in world population will make nearly all environmental problems worse. One of the first effects, though not necessarily the most visible, is likely to be a shortage of fresh water. Rivers are running dry. Water tables are shrinking. The demand for water is simply outrunning the supply. A new balance needs to be re-established between the supply of water and the use of water.²⁰

Table 2
Laboratory soil moisture profile to a soil depth of 20cm.
Soil moisture profile achieved after constant heat was applied for four days to the columns of soil in a laboratory situation.

	Soil depth (cm)	Soil moisture (%)	% Increase
Bare soil	surface	17	-
	2	17	-
	5	29	-
	10	40	-
	20	42	-
	surface	24	+ 41%
	2	31	+ 82%
	5	40	+ 38%
	10	40	no change
	20	42	no change

The top 5cm of soil is the most critical in terms of moisture conservation. The soil moisture content is substantially improved by the use of EcoCover long life mulch mat compared to that of bare soil.

Research clearly demonstrates the difference in moisture conservation that EcoCover long life matting makes to the soil. Further tests were conducted on soil moisture profiles, namely: field soil moisture at 2cm soil depth. All confirmed the results of previously published data on the benefits of mulch mats in regard to soil moisture retention.

Massey's research proved EcoCover mulch mat to have greater efficiency than either bare soil or black plastic in conserving soil moisture, with significantly higher moisture levels in the soil. Moisture content in black plastic and bare soil treatments were very similar.

Bare soil allows for the evaporation of valuable moisture and black plastic film prevents the transfer of moisture through the film into the soil and therefore exhibits a similar soil moisture profile to that of bare soil. Black plastic prevents the transfer of moisture through to the soil other than a minimal amount through the plant stem hole.