NutraFarm Complex Cover Crops

Cover crops

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Harvest in almost over and hopefully the drought has not affected your tonnage too much. Its almost time to start thinking about what’s next for our vineyards. Many of us (we certainly don’t) do not have enough water to give a post-harvest fertigation. So what can we do to build our soils, water infiltration rates and water holding capacity that is cheap?The answer is a diverse cover crop.

We at NutraFarm have pioneered diverse high diversity cover cropping here in SA and have seen great results and on our clients farms. Based on our experience from last year, we will be offering two options for the 2018 season:

The Ultra-premium blend – 23 species + soil activator - R1370.78 per hectare

The Premium blend – 20 species + soil activator - R 973.85 per hectare

Here are some of the benefits of a diverse cover crop:

PROTECT SOIL FROM EROSION: The foliage of cover crops reduces the velocity of raindrops before they hit the soil surface, preventing soil from splashing. This prevents slaking of soil aggregates and sealing of the soil surface. (When this occurs, runoff increases, along with soil erosion). The roots of the cover crops bind soil particles together, improving soil structure and water penetration, while preventing the soil particles from moving.

REGULATE VINE GROWTH: Cover crops can be used to both invigorate vines (augmenting soil nitrogen from nitrogen-fixing legumes) and de-vigorate vines (root competition from non-legumes with the vines for nutrients and water).

IMPROVE SOIL FERTILITY: Besides increasing soil nitrogen, decomposed cover crops increase the soil cation exchange capacity. Therefore, the ability of a soil to hold and exchange nutrients increases. Additionally, nutrients are often chelated into organic complexes, and are more readily exchanged from these substrates than from inorganic clay minerals.

IMPROVE SOIL STRUCTURE & WATER HOLDING CAPACITY: Initially, cover crop roots help aggregate soils as fine roots penetrate the soil profile (especially grasses). Cover crops with large tap roots help to create macropores when the plants die, and a void is left from the decomposing roots. These macropores greatly assist the movement of air and water into the soil profile.Soil organisms using the decomposing cover crops as a food source create waxes and other sticky substances that hold the fine particles into aggregates, lowering bulk density and improving soil tilth. As organic matter increases in the soil, so does the soil’s ability to hold water.Physical improvement of the soil is important, because, large root systems are very desirable in organic winegrowing. Since soil nutrient concentrations may be lower than conventionally farmed vineyards, and since many organic winegrowers prefer not to irrigate, a root system that forages through a larger area of the soil profile is more likely to provide what a vine needs.Many organic winegrowers feel that relying more on the soil than on a bag of soluble fertilizer applied through the drip system to provide water and nutrients will be a better expression of a vineyard site’s terroir.

ENHANCE BIOLOGICAL DIVERSITY IN THE ROOT ZONE: Organic matter is a food source for macro- and micro-organisms. Many of these organisms assist in recycling cover crops into the soil, while improving soil physical qualities in the process. Particularly noteworthy are increases in earthworm populations; they are a good indicator of soil health and improved physical conditions.Increased biological activity occurs in the soil after the incorporation of organic matter from cover crops. Researchers have clearly shown that these organisms can reduce damage from root pathogens by inhibiting their growth and development.

PROVIDE HABITAT FOR BENEFICIAL GENERALIST PREDATOR, PARASITOID INSECTS & ARACHNIDS (SPIDERS & MITES): Since pest management strategies in organic winegrowing emphasize reliance on nature and the use of “soft” chemicals, it is important that beneficial arthropods are abundant and in close proximity to the vineyard to control harmful insects and mites. Cover crops can provide habitat and food for beneficial insects at different stages of their life cycle. They also provide habitat for prey, such as aphids, mites, caterpillars, and other creatures. Research entomologists have a difficult time understanding the dynamics of pest and prey relationships in the cover crop, and their effects on grapevine canopies. Regardless, growers report experiences of reduced leafhopper and mite problems when cover crops are planted in lieu of conventional insecticide applications.PROVIDE FIRM FOOTING FOR HARVEST & CULTURAL OPERATIONS: When no-till, sod-forming cover crops are planted, the resulting firmer footing makes vineyard operations during wet weather more feasible. This can enable harvest, pruning, and spraying during inclement weather.

IMPROVE AIR & WATER QUALITY: Water quality laws are being increasingly enforced, and vineyard water runoff needs to be free of silt and excess nutrients. Cover crops help to prevent erosion. Nitrogen formed by legumes is less mobile than soluble nitrogen fertilisers. Cover crops assimilate free nutrients in the soil, and stabilise them during periods of high rainfall. During the dry periods of the year, cover crops help reduce dust, improving air quality. This also helps to reduce the problem of mite infestations, which intensify under dusty conditions.

Multi-species cover crops that mimic naturally-occurring diverse ecosystems are much more stable and productive than manufactured mono-cultures. Ecologists have long understood the importance of diversity in ecosystems and conclude that biological communities are more productive (in terms of biomass) and resilient when the number of species is high. Diverse plant populations use resources such as water and soil nutrients more completely, resulting in increased production. They are also more robust. The one factor common to the extremely cold and extremely hot environments in which plants and animals survive in some of the most desolate and extreme conditions on the planet is the diversity of plant and animal species in those environments.

Three main ecological phenomena contribute to the success of diverse biological communities.

Complementary - which can be explained as the whole being greater than the sum of the parts, relates to situations in which the qualities of two or more different species improve the overall system.

Facilitation - refers to a plant’s ability to influence environmental conditions in a way that helps neighbouring species thrive. Legumes facilitate the growth of non-legumes by fixing nitrogen that becomes available to the other plants. Tall plants provide shade for emerging seedlings, reducing the exposure to water and temperature stress.

The law of The Sampling Effect - states that the greater the diversity in an ecosystem, the greater the chance that a high-yielding species will be present. (The more children in a classroom, the more likely you are to find a genius). Because highly diverse systems have more complex relationships, system output is also more varied. Diversity in managed situations such as cover crops in cropping systems is important for several reasons, especially where soil regeneration is a primary driver.Different species have different root characteristics and having roots distributed through the soil profile means moisture and nutrients are accessed from different levels so no one section is depleted. Having roots distributed throughout the soil profile distributes organic matter through more of the soil volume and stimulates soil biological activity by increasing the amount of carbon available to soil organisms. It also provides greater opportunity for the interactions between roots and soil organisms that are critical to nutrient cycling.