Dairy farming and environmental protection
“... I cannot conceive of the time when knowledge of soils will be complete. Our expectation is that our successors will build on what has been done, as we are building on the work of our predecessors.” - R.S. Smith, Director of the Illinois Soil Survey, 1928
Dan Olson has 1,000-acre dairy farm, where his focus is on soil management, both from the perspective of the feeding and health of his cows and environmental protection.
The basis of soil management is the crop rotation, which, for the fields that can be grazed includes 3 years grass/forage legume ley, then maize for silage. The arable rotation is maize for grain, triticale and a grain legume for silage, sorghum for silage, oat/triticale/brassica cover crop. The use of leys and cover crops is providing organic matter, nitrogen, soil structure and weed control. There is nothing particularly novel about the rotation but yields are good – cereals and maize 70 – 80% of conventional, on average and he has some interesting experiences with the ley mixtures.
Forage mixtures. We are familiar with the advantages of diverse multispecies leys, see the ORC trials reported here http://www.organicresearchcentre.com/?go=Research%20and%20development&page=Soils%20and%20cropping%20systems&i=projects.php&p_id=19
But Dan has a forage seed business and is doing replicated forage species and variety mixtures trials; significantly what he has found is that the benefits of diversity can be achieved through the use of mixtures of varieties, not just species. So while they are more limited in the choice of forage species than in the UK, diversity can be achieved by selecting multiple varieties of perhaps just two grasses, but with different characteristics. Lucerne, red and white clover, meadow fescue and cocksfoot are all used.
Dan has built up great expertise in the choice of cover crops; mustard and legumes for use where a ley with a lot of turf is being broken, but where readily available N is needed triticale, rye or oats plus vetches are used elsewhere.
Soil biology. They are undertaking earthworm counts, the first farm that I have seen doing this in the US and getting 5 – 17 per spade square; the higher population is very good. We agreed that generally soil biology fluctuates too much to be worth doing laboratory analyses although Dan is optimistic about the value of the Solvita respiration test, which gives an indication of biological activity. He is occasionally doing the Haney soil analysis test https://www.wardlab.com/haney-info.php, or other soil health tests when he has a problem that needs to be resolved. On a routine basis he is doing soil analysis, every 3 or 4 years, using Albrecht, as are most organic farmers in the US, at Mid West labs. He was quite surprised to hear that the BCSR/Albrecht analysis is not general in the UK or Europe; in the US it is standard practice amongst organic farmers, although the soil science establishment remains sceptical.
Soil fertility. There is a strong emphasis on maintaining soil nutrient levels and the correct cation exchange ratio; as we have seen elsewhere, the analysis does result in recommendations to apply significantly more inputs than is typical on organic farms in the UK.
Dan is routinely using Chilean Nitrate or poultry manure on leys, sorghum and maize. Depending on soil analysis there are soil and foliar applications of potassium sulphate with humates and fish, and because of the low calcium soils he is regularly using Gypsum (Calcium sulphate), some being extra finely ground for a better balance of Ca and S release. Tissue analysis is regularly undertaken to check correct balance of nutrients getting into the plant.
Mycorrhizal inoculants are applied routinely and he is incorporating Gypsum in compost to capture ammonia as Ammonium Sulphate, which would otherwise be lost.
There are some novel crop experiments underway; and interesting idea is to miss every third or fourth row of maize when drilling and to spin a cover crop mix of oats, brassica and vetch at final hoeing, using a narrow tractor in the 6 foot row. Subsequently the stubble and undersowing is grazed; the 10% yield drop is more than compensated by the forage yield.
Dan is working with the Environmental Protection Agency (EPA) to develop schemes to support farmers in addressing the serious phosphate pollution – its not just a recent problem, hence the local town name of Green Bay! Phosphate fertiliser application rates in the area are not particularly high, neither conventionally nor organically, but serious phosphate losses are caused by soil erosion and high manure application rates. The principle practices advocated are: cover cropping, better manure management and, for the conventional farms the introduction of rotations with long leys.