Direct drilling of oilseed rape through cereal straw residues: testing and development of two drills

Abstract

A two year investigation was carried out to develop direct drilling techniques in the presence of straw residues. In order to highlight potential short-comings of this technique, difficult soils in terms of their suitability for direct drilling were selected using a classification system developed by Cannel et al. Work was concerned with the testing and further development of two direct drills:

1) a cross-slot coultered drill developed in New Zealand, and

2) a single disc coultered drill manufactured by Moore Uni-drill.

The performance of both drills was initially tested in short term crop establishment trails through a range of soil, straw and climatic conditions, and then in comparative trials, in conjunction with ADAS, which were taken through to harvest.

Following modifications to both drills, performance in dry conditions was found to be very satisfactory providing adequate penetration was achieved. Problems were, however, encountered when drilling in wet conditions. In particular, prolonged waterlogging and slug attack seriously affected crop establishment at a number of sites.

Better yield results were achieved where straw was removed prior to direct drilling, however, in general, the direct drilling suitability classifications for the sites were reflected in the results. Direct drilled plots produced yields approximately 15% lower than those from conventionally cultivated plots.

Investigations over the past two years have provided a valuable insight into factors affecting the performance of direct drilled crops in the presence of straw residues. The results suggest that, with further development, this technique has considerable potential, however, due regard must be given to a soil's suitability for direct drilling particularly if the season proves to be wet.