Agriculture Reference
In-Depth Information
200
Arable
Beef
Dairy
Horticulture
Mixed
150
100
50
0
Nitrogen
Phosphorus
Potassium
-50
Figure 3.1
Average farm-scale nutrient budget surpluses (average input minus output) for
nitrogen, phosphorus and potassium on various organic farm types in temperate countries (after
Watson
et al.
2002).
manure, slurry and green manure) on crop production and soil properties indicated that large
amounts of manures and other organic inputs were needed to get improved soil chemical and
physical properties, but crop yield was not affected.
Green manures
The cultivation of crops that are not devoted to selling or feeding purposes is commonly
understood as green manuring. Older definitions focused more on the fertilising aspects that
were achieved by incorporation of crops in an immature stage. More recent understandings
30
25
20
15
10
Conventional
Organic
5
0
1960
1965
1970
1975
1980
1985
Time of conversion to organic farming
Figure 3.2
Phosphorus concentration in the top 20cm of soil for German farms converting to
organic practices in the years from before 1960 to 1984 compared with paired conventional farms
(after Lampkin 1990).
