Whole-rotation dry matter and nitrogen and grain yields from the first course of an organic farming crop rotation experiment

Olesen,-J-E; Rasmussen,-I-A; Askegaard,-M; Kristensen,-K
Research Centre Foulum, Department of Crop Physiology and Soil Science,
Danish Institute of Agricultural Sciences, Box 50, 8830 Tjele, Denmark.
JorgenE.Olesen@agrsci.dk

Abstract
The possibilities for increasing total grain yield in organic cereal production through manipulation of crop rotation design were investigated in a field experiment on different soil types in Denmark from 1997 to 2000.

Three experimental factors were included in the experiment: (1) proportion of grass -clover and pulses in the rotation, (2) catch crop (with and without) and (3) manure (with and without). Three four-course rotations were compared. Two of the rotations had one year of grass-clover as a green manure crop, either followed by spring wheat or by winter wheat. The grass-clover was replaced by winter cereals in the third rotation. Animal manure was applied as slurry in rates corresponding to 40% of the nitrogen (N) demand of the cereal crops. Rotational grain yields of the cereal and pulse crops were calculated by summing yields for each plot over the 4 years in the rotation.

The rotational yields were affected by all experimental factors (rotation, manure and catch crop). However, the largest effects on both dry matter and N yields were caused by differences between sites caused by differences in soils, climate and cropping history. The rotation without a green manure crop produced the greatest total yield.

Dry matter and N yields in this rotation were ~10% higher than in the rotation with a grass-clover ley in one of 4 years. Therefore, the yield benefits from the grass-clover ley could not adequately compensate for the yield reduction as a result of leaving 25% of the rotation out of production.

There were no differences in dry matter and N yields in grains between the rotations, where either spring or winter cereals followed the grass-clover hay. The N use efficiency for ammonium-N in the applied manure corresponded to that obtained from N in commercial fertilizer. There were only very small yield benefits from the use of cash crops. However, this may change over time as fertility builds up in the system with cash crops.

Source
Journal of Agricultural Science. 2002; 139(4): 361-370

 

 

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Posted September 2007