Assessment of crop residue cover with photographic slide and point intercept methods

A sugar cane intercropping study was conducted at the Waimanalo research station of the University of Hawaii during 1993-94. Sugar cane was planted as the main crop and sweet corn and wheat were planted as intercrops at 0, 75, 150, and 300 kg N ha(-1). After the harvest of the sweet corn and wheat, the senesced and harvested crop plants were left and evenly spread in the field between the sugar cane rows. The residues of the intercropped sweet corn and wheat plants were used to compare the amount of residue cover with the photograph slide method and the point intercept method. The average per cent residue cover was significantly higher in wheat than in sweet corn at 0 and 75 kg N ha(-1). Application of 150 kg N ha(-1) produced maximum residue cover. Results indicated that both methods produced similar estimation of crop residue cover at 75, 150, and 300 kg N ha(-1). The photographic method gave a significantly higher crop residue cover than the point intercept method in the 0 kg N ha-(1) treatment. Both the point intercept method and the photographic method gave similar estimation of crop residue cover. The results of the study showed that the point intercept method is easier and economical to estimate crop residue cover than the photographic slide method. However, the photographic slide method has the advantage of producing a permanent record that could be revisited.