Pasture and Cover Crop Seed from Barenbrug.
A presentation was given by a RSA-based Barenbrug representative to members of the Regen Group (Regenerative Farmers Group) on 14 Jan 2020. Dr Doug Bruce hosted it at his offices alongside Borrowdale racecourse.
Barenbrug is a Dutch company that specializes in pasture and forage crops for livestock as well as cover crops for mixed farming. Cover crops have a role to play in improving soil health, which is a concept, which is steadily gaining acceptance even in mainstream agriculture. Aggressive tillage is generally avoided in agriculture nowadays, as the concept of Conservation Tillage has found wider acceptance.
Cover crops take the concept further by addressing soil compaction and improving soil structure. To address compaction, a crop with dense, fibrous roots would be chosen for the first season. The land would be ripped and the loosed soil would be filled with fibrous roots.
The Barenbrug system of choosing cover crops pays attention to the Ca: Mg ratio in the soil, and testing for this is crucial. The test will indicate any need to add lime, and at what rate. Fibrous root cover crops include sorghum, triticale, rye, oats. For heavier clay soils barley and stooling rye are used. Part of the Barenbrug concept is to use mixtures of a range of fibrous root crops, with the ratio worked out for specific soil types. Planting fibrous root crops primarily to improve soil structure seems a bit of a luxury in present-day Zimbabwe, but locally-available commercial varieties of sorghum, mhunga or barley could presumably be incorporated into the rotations.
Following fibrous root crops, cover crops to improve crop nutrition and soil microbes are the next part of the program. These could include legume covers such as lupines, serradella, sun hemp for sandy soils, vetch, medics, clovers, cowpeas and dolichos beans for clay soils. Brassica cover crops such as white mustard and fodder radish could also be included. Barenbrug supplies seed for all the cover crops mentioned and has decades of experience with combinations of these grasses, legumes and brassicas in Europe.
The above concepts have been tested in South Africa and research work is ongoing. Locally, at least 3 farming operations are currently working with Barenbrug varieties to improve pasture in mixed farming. Since the varieties originate from Europe, a program of local testing will be required to show which varieties and combinations are best for Zimbabwe. Funding of local research is a question that still needs to be addressed.
In most parts of the world, the tenure of farmland is known with a high degree of certainty and the custodians of the land invest it with care. It is encouraging to see that the concepts being advanced by Barenbrug are being endorsed in South Africa and even Zimbabwe.
Barenbrug sees the need to measure soil micro-organism (MO) activity and makes use of the Haney test to estimate the percentage of fungi, bacteria and nematodes in the soil. MOs and plant root hairs produce great quantities of exudates, the importance of which is starting to be more widely appreciated. The exudates are the gums and glues that hold soils together and make them richer and more complex. Cover crops can be chosen to encourage MOs and mixes of grasses and legumes have a role here. By adding structure and complexity and planting cover crops, soils are letter able to retain water, which is important in seasons such as this one where the rains have been heavy, followed by lengthy dry spells.
How does one start with this form of regenerative farming?
In RSA, farmers have replaced a cash crop or grain crop with a summer cover crop. Typically such a cover crop would be fertilized at 60 – 70 % of the level normally required for a maize crop. The legume in the cover crop mix would build up Nitrogen levels for the next crop. Studies have shown in certain areas of RSA, a summer cover crop grazed by livestock has made a better return than a normal maize crop, with the added benefit of elevated nitrogen levels for the following crop.
Alternatively, farmers have started with a winter cover crop which loosens up the soil and would allow the following soyabean crop to get an early start to the season. Barenbrug also promotes the Covergraze concept in parts of RSA, where forage sorghum or sweet sorghum planted in mid – summer to April and is grazed through the mid – winter period.
The Barenbrug concept of soil improvement using cover crops is still new to Zimbabwe. A follow up article giving further details will appear in this space in the near future. Further details can be obtained from Neil van der Merwe [email protected] or 0772 214 116.
Stewart Wilson