Possibilities and Limits of Reduced Primary Tillage in Organic Farming

Project Titel:	Possibilities and Limits of Reduced Primary Tillage in Organic Farming

Project Responsible Name:	Christina Vakali

Partners:

Duration:
Funded by:	Stiftung Ökologie und Landbau, DAAD

Keywords:	reduced primary tillage, Winter cereals, root-length density, yields

Abstract:	Introduction In two organically cultivated held trials, located in Germany and Greece, effects of reduced primary tillage systems on root and shoot growth of cereals were investigated. The held trial in Ronmiershejm near Mainz, Germany, was established in 1994 by the foundation ,,Stiftung Ökologie und Landbau." The Agricultural University of Athens established in 1995 a similar experiment in a held trial carried out by of The Laboratory of Crop Science, located in Athens, Greece.
	Materials and methods Mouldboard plough, two-layer plough and layer cultivator were used in Germany. Mouldboard plough, rotary hoe and zero tillage were applied in Greece. The field experiment in Germany was performed on a clay loam soil (Calcaric Regosol, FAO) with a 5-year crop rotation (green fallow, Winter wheatlcatch crop, peas, Winter ryelcatch crop, spring barley) in a split-plot design. The investigated crop was spring baliey. Tillage systems were implemented after cereal harvests only. The held experiment in Greece was perforrned on a clay loam soil (alluvial, Typic:Argids, soil taxonomy, USA) with a 3-year crop rotation (cereal, green manure, cotton) and a split-plot design. The test crop was Winter wheat. The parameters measured every year were: aggregate stability, penetration resistance, root-length density, shoot dry matter, leaf area index, soil surface cover by crops and weeds and crop yield. N, P and K were analyzed in shoot dry matter ofcrops and weeds. Soil nutrient parameters were: C,/N~, Nmin, P and K contents.
	Results and discussion In Germany, higher tillage intensity increased rooting density, nutrient uptake and crop development. Dry matter production of weeds was significantly lower in the ploughed fields compared with those treated with the cultivator. Correspondingly, higher grain yields were positively correlated with tillage intensity. Positive effects of the cultivator on soil properties (e.g. significant higber aggregate stability compared to ploughing) became less significant. In the experiment field ofAthens, under minimum tillage (zero tillage and rotary hoe), it was found that root system parameters were significantly higher than those of ploughed plots. Physical, chemical and biological soil properties were also improved compared to those of ploughed soil. Yields were found to be significantly correlated to the root parameters and the soil properties, and this was conhirmed by the significant yield increase observed under minimum tillage.