Permanent pasture

It is generally assumed that leys will out-yield permanent pasture. The main reason for this assumption is that by definition leys are grown on fields that can be ploughed, whereas permanent pasture is mainly on steep, stony or inaccessible land which is difficult or impossible to plough. It is not therefore the sward constituents that are determining the difference in yield, but the soil type, depth, pH and nutrient status. 

The most satisfactory method for the organic farmer to reduce the risk of infection to lambs from internal parasites is to practise clean grazing, which reduces parasitic infection and increases lamb growth rate (Fig. 3.5). The most effective method of clean grazing is, as we have seen, to use a three year rotational system with sheep, followed by cattle, and then arable. This presupposes land that can be ploughed. On permanent pasture farms with no arable, beef and sheep should be alternated. To make this effective, it helps if there are as many beef livestock units as sheep. If the farm contains only sheep, then it is advisable to alternate on an annual basis between ewes with twins and ewes with singles. If the flock normally produces mostly... 

Most farmyard manure is produced by overwintering beef animals indoors, and as most beef and sheep farms are situated on permanent pasture in steep or rocky areas, it is the application of farmyard manure to grassland that is most usual, particularly to fields that are cut for silage or hay. 

The preventive procedure relies on putting worm-free animals on a parasite-free or a clean pasture. Clean areas may be new leys or can be provided on permanent pasture by alternating with other livestock species not sharing the same spectrum of parasites, or by use of aftermath after harvesting a hay or silage crop (this procedure is generally difficult to apply under practical farming conditions). 

Clements, R.O., P.J. Murray, and C.J. Tyas. 1992. The short-term effects on wild goose behaviour of chlorpyrifos application to permanent pasture. Ann. Appl. Biol. 120 17-23. 

Howard, F.W. and A.D. Oliver. 1978. Arthropod populations in permanent pastures treated and untreated with mirex for red imported fire ant control. Environ. Entomol. 7 901-903. 

Slattery, J. F. and Coventry, D. R. 1995. Acid-tolerance and symbiotic effectiveness of Rhizobium leguminosarum bv. trifolii isolated from subterranean clover growing in permanent pastures. Soil Biology and Biocheistry, 27 111-115. 

Table 5.1 Percentage of land in crops, fallow, temporary and permanent pasture devoted to cereal production during 1875-1985 (DEFRA, 2002)a...

Barber, D.A. Mitchell, W.A. (1964) The entry of caesium-137 and strontium-90 into the herbage of permanent pasture. In ARCRL Report 12. Agricultural Research Council Radiological Laboratory. Letcombe, Oxon., pp. 59-61. 

Arable and permanent crops are grown on 7.6% of the SSA land area, permanent pasture covers a further 30.4% (FAOSTAT, 2006). The major farming systems that evolved in the diversity of African environments are described below (Fig. 1) (e.g. Dixon et al., 2001) ... 

In Asia, there are three important uses of land arable or croplands, permanent pastures and grazing land, and forest and woodlands. The land use pattern in the region has undergone a major change over the years with a sharp increase in cropland but a marked decline in forest. The growth in cropland is characterized by three phases (Figure 2). 

Co untry/region Total land area Arable and permanent crops land Permanent pasture Forest and woodland Other lands ... 

Aslam, T., Choudhary, M.A. and Saggar, S. (1999) Tillage impacts on soil microbial biomass C, N and P, earthworms and agronomy after two years of cropping following permanent pasture in New Zealand. Soil and Tillage Research 51, 1 03-111. 

Fig. 12.2. The increase in water-soluble organic phosphorus after soil drying as a function of soil microbial phosphorus in a wide range of permanent pasture soils from England and Wales (Turner and Haygarth, 2001). Water-soluble phosphorus was determined by extracting soils at field moisture capacity with water in a 4 1 solution/soil ratio for 1 h. Subsamples were air-dried for 7 days at 30°C and extracted in an identical manner.

In addition to providing water and physical support for plants, soil properties and processes regulate the cycling, retention and bioavailability of the major elements (Daily et al., 1997). Most of the phosphorus in terrestrial ecosystems is present in the soil. On a global scale it has been estimated that soil contains 96-160 X 10 Mg of phosphorus compared with only 2.6X10 Mg in biota (Stevenson and Cole, 1999). The proportion of total ecosystem phosphorus present in soil varies widely. For example, in a grazed permanent pasture, herbage phosphorus represented only 1% of the total phosphorus in topsoil (0-20 cm) (Williams and Haynes,... 

Barley (1959a) observed that in a 4-year rotation of two years of grass, one of fallow and one of wheat, the weight of the worms after the fallow and crop years was only a quarter of that found on permanent pasture, but after the grass the weight almost equalled that on permanent pasture. 

Temporary pastures often consist of a single, sown plant species, whereas permanent pastures include several species of grasses and legumes. Natural grasslands consist of a wide variety of plants, including shrub species. 

Some cropping systems are much more prone to water erosion than others. The most susceptible land use is when crops are harvested in the auturrm under adverse soil conditions which can happen with forage maize and field vegetables. Long term leys and permanent pasture usually pose little risk. Soils with a good crop cover are much less susceptible than where there are fine seedbeds and or bare ground. 

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