A rising demand for environmentally friendly production practices, combined with escalating fertiliser prices, forces farmers to find more natural and economical ways to optimise production. Bennie van Greunen tells Glenneis Erasmus how clover helps him and his brothers attain this goal.
The Van Greunens have always placed a high premium on environmentally sound production practices. “My father Ben adopted them long before the term environmentally friendly was even coined,” says Bennie van Greunen, who farms with his brothers Johan, Nelius and Christie at Van Greunen Boerdery near George in the Western Cape.
“To him it was common sense to use crop rotation and mixed-crop pastures to overcome problems associated with monocropping. Agricultural magazines have been writing about his rotation system since the early 1980s.” Today, 80% of the pasture at the Van Greunens’ farms are a grass-clover mixture. Drymatter production on mixed pasture is lower than on pure grass pasture such as kikuyu, sometimes by up to 20% depending on production conditions, but fertiliser costs are far lower due to clover’s nitrogen-fixing ability.
Milk production is also better on grass/clover than pure grass pasture. John Fair in his Guide to Profitable Pastures: Part 1 estimates using a grass-clover combination can increase milk production by 15% to 25%. He says excessive nitrogen use, as often occurs on pure grass pasture, can yield nutrient-deficient, low-energy forage.
“Nitrogen has almost the same effect as a rubber band,” he explains. “Plants elongate, but nutrients are diluted.”
Pasture nutrition
Mixed pasture must receive the correct minerals to reach full production and nutritional potential. Soil analysis and correcting soil nutrient levels are crucial.
At the Van Greunen Farms soil sampling and analysis are guided by variations in soil and production. Only one soil sample might be taken on land with uniform production, while more would be needed in one with varying soil characteristics and production. The soil is corrected according to analysis results before establishing a new pasture or crop.
Liming is especially important as the soil is naturally acidic with a pH (KCL) of 3,8 to 5. Rectifying the pH makes soil nutrients more available to plants.
Grass-clover pasture is maintained for four to five years depending on its condition, and withdrawn from production for a year before being re-established. Vegetable crops are grown with compost during this break. To increase soil-organic content, compost and vegetable residue are worked back into the soil before new pasture is planted.
Fertilising pasture
Dairy manure is returned to the pasture for its high nutrient content and to increase soil organic content. It’s applied either via irrigation systems or, if it’s too thick, pumped directly out of manure ponds and spread onto the land.
Pastures receive two to three 8mm/ha manure-water applications a year, depending on requirements. Pasture fertilised with manure must be carefully monitored, as its rich nutrient content can overapply nutrients such as potassium, phosphorous, magnesium or sodium. “Excesses can render the pasture toxic and even cause mortality,” warns Bennie. “Soil analysis helps monitor mineral and nutrient levels and identify potential risk.”
An effective microorganisms (EM) mix is sprayed onto the manure in the lands. Microorganisms produce bioactive substances, vitamins, hormones, enzymes, amino acids and antibiotics, which enrich and detoxify the soil. This way EM can enhance plant growth and make plants more drought, frost-, pest- and disease-resistant.
Bennie also adds 20ml of EM to each cow’s daily supplement in the milking parlour. He believes it’s good for digestion and has a positive effect on reproduction and health.
Strategically used nitrogen in the form of urea or limestone ammonium nitrate (LAN) maintains fodder flow after excessive rain. Bennie says too much water can cause plants to “stand still”, and nitrogen helps kick-start them back to life. Urea is used after summer and spring rain. LAN is used in winter because the enzymes making nitrogen available from urea are inactive in cold conditions.
No more than two applications of 45kg/ha and 50kg/ha of nitrogen are made each year, via the irrigation system. They’re applied with 2kg/ha of humic acid, which has a stabilising action, reducing nitrogen loss.
Establishing pasture: the secret in the mix
The grass-clover pastures are seeded with a mixture of perennial ryegrass seed (cultivars Bronzyn and Bealey) at 10kg/ha, and 10kg/ha clover seed consisting of two white cultivars (Haifa and Waverley) and two red cultivars (Red Gold and Quinequeli). Red cultivars are summer growers and white cultivars are autumn or winter growers, so the mixture ensures the clover is available longer.
Grass-clover pasture has a carrying capacity of three to four cows per hectare under favourable conditions. It’s best grazed when ryegrass reaches the three-leaf stage. Ryegrass regrowth takes three to five weeks, depending on soil temperature.
Earlier grazing will compromise photosynthesis, and plants won’t have enough energy to produce new leaves. However, late grazing will kill the third leaf, resulting in wasted forage, unpalatable roughage and overshadowed growth points, preventing the development of new daughter tillers and shortening the life of the pasture.
Bennie moves the cattle out of the pasture when it has been grazed down to 1cm. He stresses the importance of a high intensity, short-duration grazing system on grass-clover pasture to avoid selective grazing, which can wipe out red clover and must also be avoided at all costs. Therefore a mobile electric fence limits the grazing period to one to two days.
The grass-clover pastures are augmented with lucerne, cocksfoot, and annual ryegrass to maintain fodder flow in winter, along with ungrazed pasture and silage made from 150ha to 200ha of maize. Bennie says they aim to buy as little feed in as possible – the only thing not produced on the farm is the maize-based energy feed used in the parlour. Contact Bennie van Greunen
on (044) 8810110 or e-mail [email protected]. |fw
