Critical evaluation of the Kemink Exact Soil Management System and its components

By Christian Bugge Henriksen and Jesper Rasmussen, Royal Veterinary and Agricultural University, Department of Agricultural Science.

Organic farming is based on principles, which include alternative concepts of soil fertility. Instead of just feeding the plants with nutrients, the farmer should build and maintain a fertile soil. Since the complete inversion of soil associated with ploughing does not harmonize well with the alternative concepts of soil fertility, the development of alternative tillage systems for organic farming is highly relevant. The Kemink Exact Soil Management System represents such an alternative tillage system, and in a Ph.D. thesis to be published later this year (Henriksen 2004), the Kemink system and its components are evaluated.

Characteristics of the Kemink system

The Kemink system was developed by the German farmer and inventor Hans Kemink (Fütterling 1984). It is characterized by ridging, frequent subsoiling and controlled traffic. All field operations are performed using a special frame on which different implements for subsoiling, ridging, seedbed preparation and mechanical weed control can be mounted.

In the Kemink system, the purpose of ridging is to increase the surface volume of the soil, enhance the decomposition of organic matter and thereby release nutrients to the soil. Instead of ploughing crop residues down, they are incorporated in ridges in autumn. The purpose of subsoiling in the Kemink system is to loosen the soil to a greater depth than it is possible by ploughing and thereby secure a deeper root growth. With a special type of winged subsoiler, the top 35-40 cm of the soil is subsoiled before, during and after the growing season, and it is possible to maintain the soil in an extremely loose condition. The purpose of controlled traffic in the Kemink system is to avoid recompaction of the subsoiled soil. Controlled traffic is applied by using permanent tracks.

Farmer experiences

Since the first demonstration of the Kemink system in 1976, it has been used by several farmers in Germany. In a questionnaire with 28 farmers using the Kemink system, 89% reported that soil structure and water holding capacity was improved by the Kemink system, 91% reported that root volume was increased and 63% reported higher yields (Fütterling 1984). However, 56% reported that weed problems were increasing and 80% of the farmers experienced a higher workload.

One farm in Denmark has been using the Kemink system for 13 years and is still obtaining good yields. This is remarkable because farmyard manure or green manure has not been applied. Many farmers, advisors and students have visited the farm, wondering how it has been possible to maintain a good yield without fertilization. On-farm studies have shown that root mass and root depth of brussel sprouts (Brassica oleracea L.) was higher on this farm compared with an adjacent farm (Søgård 1995) and soil samples showed no sign of decrease in the level of phosphorus, magnesium and potassium during 1986 to 1997 (Søgård 1995, 1998).

Field experiments

In three series of factorial field experiments, conducted on loamy soil at the agricultural research station of the Royal Veterinary and Agricultural University of Denmark, the Kemink system and the isolated components, ridging and subsoiling, were compared with a traditional tillage system based on mouldboard ploughing. This reductionistic approach was successful when investigating the isolated components of the Kemink system, but failed to provide a clear evaluation of the Kemink system as a whole during a three-year period.

Ridging in autumn resulted in significantly lower levels of inorganic nitrogen in the 30-90 cm soil layer in late autumn and a significantly higher level of inorganic nitrogen in the 0-30 cm soil layer in spring. This indicates reduced leaching and increased nitrogen availability for the subsequent crop. The improved soil nitrogen status was confirmed by increased growth, yield and nitrogen uptake of a subsequent barley crop. This shows that ridging in itself could be a potential alternative to ploughing.

Kemink subsoiling after planting damaged the plants and generally had a negative effect on growth and yield of barley and sugar beet, whereas subsoiling before planting increased sugar beet yield with 12% compared with ploughing. There was no effect of subsoiling before planting on the grain yield of barley and the negative effect of subsoiling after planting was more pronounced for barley. It is concluded that Kemink subsoiling before and after planting is problematic, since Kemink subsoiling before planting can only be performed when the soil is dry and Kemink subsoiling after planting may damage the crop.

Evaluation of the Kemink system in its entirety

The major series of experiments, in which the Kemink system was investigated in its entirety, showed that it was difficult to establish a proper seedbed with the Kemink implements. This resulted in reduced crop emergence. Furthermore weed infestation was increasing over the years due to insufficient weed control. Despite a looser soil, created by the Kemink system, there was no general impact on crop yield. There was, however, a positive crop yield development over time showing that yield in the Kemink system changed from being relatively lower in 1998 and 1999 to the same level as in the traditional tillage system in 2000.

In the PhD thesis it is discussed whether the problems encountered with the Kemink system as a whole, including increased weed infestation, could be due to the fact that the experiment was conducted as series of simplified field experiments on a research station and that the object under investigation was a young Kemink system in transition, instead of a mature Kemink system. Furthermore it is discussed whether the reductionistic approach is suitable for studies of the Kemink system and other complete management systems, or if a holistic approach would be more appropriate. When published the PhD thesis will be available for download at Organic Eprints.

References

Fütterling, L. (1984). Das Kemink-Exact-Bodenbearbeitungssystem in der landwirtschaftlichen Praxis. Diploma thesis. Gesamthochschule Kassel, Witzenhausen, Germany.

Henriksen, C.B. (2004). Alternatives to ploughing in organic farming – The Kemink Exact Soil Management System and its components. PhD Thesis. In press.

Søgaard, C. (1995). Kemink exact jordbehandlingssystemet - et økologisk alternativ? Masters Thesis. Royal Veterinary and Agricultural University, Denmark (in Danish).

Søgaard, C. (1998). Jordbehandlingen skal holde liv i jorden. Økologisk Jordbrug, 167, 10 (in Danish).