Annual and seasonal changes in production and composition of grazed clover-grass mixtures in organic farming

Abstract

A grazed field experiment based on a randomised block design was conducted in Eastern Finland to evaluate the potential of alsike clover (Trifoliun hybridum L.), red clover (Trifolium pratense L.) and white clover (Trifolium repens L.) to support herbage production from clover-grass mixtures under organic farming practices. The effect of seed mixture (alsike clover, red clover, white clover, white and alsike clover or grass mixture), year (1996, 1997 and 1998) and grazing period (5 per grazing season) on pre-and post-grazing herbage mass (HM), botanical and chemical composition of pregrazing HM and post-grazing sward height was assessed. The nutritive value of herbage for milk production was also considered. Seed mixtures resulted in different pre-grazing HM and post-grazing sward heights, but similar pre-minus post-grazing HM. Compared with other mixtures, the proportion of clover was higher for white clover based mixtures. The white clover mixture had the highest crude protein content and lowest concentrations of cellulose and hemicellulose. In addition to seed mixture, the effect of year and grazing period on measured parameters was significant, highlighting the importance of grazing management. Moderate pasture herbage production of relative high nutritive value was achieved under organic practices, but the supply and nutritive value of herbage was variable and, in some cases, unable to meet the requirements of lactating dairy cows. The proportion of clover in all seed mixtures decreased year on year, and was subject to seasonal variations that altered the nutritional value of herbage. White clover was the most suitable perennial clover for pastures in Eastern Finland.

Annual and seasonal changes in mineral contents (Ca, Mg, P, K and Na) of grazed clover-grass mixtures in organic farming

“…15 (2006. mg l -1 ), with an organic matter content between 60-120 g kg -1 dry matter (DM) and a mean pH (water) of 6.1 (Kuusela 2004 [1997][1998] with five grazing periods (GP1-GP5) per annum. During the experimental summers the replicates were rotationally (21 day cycle) grazed five times per summer by lactating Ayrshire dairy cows applying a mean stocking rate of 3.5 and 2.9 cows ha -1 for 1997 and 1998, respectively.…”

“…Samples collected from the current experimental field during 1996 and pooled on the basis of seed mixture suggested higher mean Ca and Mg contents of the herbage, but similar potassium (K), phosphorus (P) and sodium (Na) concentrations compared with conventional grass pastures (MTT 2004, Kuusela, unpublished data). The botanical proportions of organic pastures are subject to between-season and within-season changes (Kuusela 2004), which may affect the mineral supply for grazing animals. Besides shortage or excess of individual minerals, also mineral imbalances can be detrimental to animal health and welfare (Hovi et al 2003).…”

“…This study is connected to the study 'Annual and seasonal changes in production and composition of grazed clover-grass mixtures in organic farming' (Kuusela 2004). The effect of seed mixture, year and grazing period on the calcium, magnesium, phosphorus, potassium and sodium contents of pre-grazing herbage was studied, the relationships between the botanical proportions and mineral contents were considered and, finally, the implications for dairy cows' mineral feeding are discussed.…”

“…Pre-grazing herbage samples were taken manually by cutting six randomised areas (74.0 cm × 22.5 cm) to a height of 3 cm above ground level using shears and an aluminium frame (Kuusela 2004). Each homogenised sample was divided for DM determinations (100 g), chemical analysis (200 g) and botanical analysis.…”

Legumes in Finnish agriculture: history, present status and future prospects

“…can produce good yields in our conditions (Varis 1986), but they are used rarely in ley production. Modern cultivars of white clover were found to be well adapted to pasture use in Eastern parts of Finland (Kuusela 2004). The forage legumes are generally grown in mixtures with grasses including timothy, meadow fescue (Festuca pratensis L.) and tall fescue (Festuca arundinacea L.).…”