Summary of final report:
As part of SOLID WP1, on-farm research actions took place in Eastern Finland in 2013 and 2014 in order to increase the protein self-sufficiency of organic dairy farms. A mixture of red clover and grasses was studied as it is the most common sward composition for silage in organic farms.
The aims of the on-farm trials were 1) To study the effect of grass topping on the clover content and forage protein production in the first silage cut and 2) To study the effect of the autumn application of slurry on the protein content of the companion grass and forage protein production in the first silage cut of the following spring. Topping and autumn slurry application were studied in two and four organic fields, respectively. Besides research questions, two different methods of conducting on-farm research were tested. Trials involved the use of farm scale machines and small plot measures of 0.25 m2 taken by a researcher.
In the topping trial the exceptionally warm growing season in 2013 resulted in more vigorous and rapid early growth of red clover than usually. The difference in height between red clover and grasses was not great enough in early growth stage in May to top grass without damaging red clover. Time between topping and the first harvest was too short (less than two weeks) for red clover to develop and to increase protein content of the forage. Topping did not increase clover content of the first silage cut but rather on the contrary. However, the organic dairy farmers gained by one cut from un-topped organic red clover-grass a valuable yield of 4800, 3270, 560 and 380 kg ha-1 dry matter, digestible organic matter, crude protein and metabolizable protein, respectively.
In the trial of autumn slurry application three fields received 20 t ha-1 digestate of organic cattle slurry directly injected into the red clover-grass. The fourth field received 20 t ha-1 aerated organic cattle slurry broadcasting on soil surface. Slurry application in autumn increased crude protein content of grass (116 vs. 125 g kg-1 DM) and total crude protein yield (397 vs. 455 kg ha-1) in the first silage cut of the following year. Concentration of soil nitrogen differed according to field due to soil type but no difference between treatment areas was found before the start of the trial. Effect of slurry application both on soil nitrate and ammonium nitrogen was clearly observed after five weeks of application. The effect could still be detected in soil soluble nitrogen the following spring. With slurry digestate 62 kg ha-1 soluble nitrogen was applied at the depth of four cm. Soil soluble nitrogen of 14 kg ha-1 at the ploughing layer was estimated to mineralize in spring. At the first silage cut 47 and 73 kg N ha-1 in grass and in total red clover grass yield, respectively, was harvested.
The conclusion from the results was the same despite the harvesting method although yield of large scale harvesting averaged 72 % of that from small plot sampling in all farm trials. Under scarcity of funds for research on organic production, on-farm research is a valuable tool to develop the sector. The most important phases in the on-farm research process were the discussions with farmers, advisors and researchers to define the questions before, and to conclude from results and experiences after the experimental work.