ABSTRACT
The “Lautenbach” scheme is à new type of experiment to develop integrated crop protection methods (as defined by FAO) on à commercially-run agricultural holding where the rules of operating efficiency must be complied with. The scheme may be regarded as comprehensive because it is founded on experience in à variety of specialized branches of agricultural production. The focal point of attention is no longer one single pest or one single crop but the farm itself with its entire cropping scheme. Because of the demands of the integrated scheme, the following production techniques were modified on the experimental holding :
Rotation :
The new system of rotation is an improved three-year rotation scheme involving six crops. In this scheme, winter wheat is grown on the same land every three years, while oats and barley return to the same land every 12 years (Eyespot/Selworm). For sugarbeet, the cultivation interval is at least four years (beet eelworm) and for peas eight years (eelworms and fungal pests). The grain/leaf crop ratio is l/l (selection of certain types of weed?!). Summer and winter crops are distributed between the allotted fields on the basis of existing weed species.
Tillage :
The effect of annual ploughing is to restructure the topsoil completely, together with all the organisms living in it and on it. Consequently, the structure of the soil and the biotopes of the organisms present are. disturbed, the weed seeds are buried (= preserved), and so on. Many of these disadvantages can be largely prevented if the soil can be similarly loosened without the structure being inverted. This has become feasible with the use of “layer” cultivators in the past three years. Provisional results are reported.
323Drilling:
Mechanical weed control is feasible only if the intervals between the rows of seeds allow the passage of the hoeing machine without damage to the crops. This is possible in the case of crops such as sugarbeet or beans. For cereals, however, the distance between rows must be increased to make hoeing at all possible. 3y combining two rows of seed in each case, for the same seed density, it was possible to increase the intervals to 24 cm. Band sowing offers à similar possibility. Various hoeing machines and the problem of cereal hoeing are discussed.
Underseeding/Catch-crop growing :
Elimination of weeds – especially summer species – and the proliferation of soil organisms can best be achieved by continuous shade over the soil. By underseeding – for instance, with black medic – in fields of late maturing cereals, or by green manuring after early maturing crops such as peas, this soil shade can be achieved even in arable farming. Examples and criteria for the selection of underseed crops are discussed.
Fertilization :
Insufficient nitrogen supplies increase storage risks and the risk of grain mould. If nitrogen fertilization is applied according to the actual requirement of the crops this risk can be considerably reduced. By determining the quantity of available nitrates in the soil (N-min-method), the first nitrogen dose (decisive for the susceptibility of wheat) for winter wheat can be calculated more accurately. Even the application of long-acting nitrogen fertilizers (e.g. Floranid, Alzon) saved the need for mould control in winter wheat in à two-year experiment involving à single dose of 75 kg of nitrogen, in the form ofrFloranid.
Chemical control :
On the land covered by the integral scheme, agrochemicals are used only where the economic damage threshold for à particular pest is exceeded. If this threshold is not known, the infestation is tolerated to the extent that it has given rise to no loss in yield in 324previous years (negative prognosis). Application of the concept of the economic damage threshold will be discussed with reference to weeds among peas.
