Field Guide. cropping and pastoral grazing on flat to rolling country.

PLANT INDICATORSCrop yield Assess relative crop yield.In a maize crop, for example, strip a number of cobs at r<strong>and</strong>om atcrop maturity <strong>and</strong> compare cob size <strong>and</strong> characteristics against thethree photographs opposite. Similar comparative assessments canbe made for wheat, barley, peas <strong>and</strong> other crops. Estimate heads orpods per square metre, grains or seeds per head or pod, <strong>and</strong> size ofgrains or seeds. Compare these with an ‘ideal’ crop.WITH A DECLINE IN SOIL QUALITY, crops can come under stress fromdrought, poor aeration, lack of nutrients <strong>and</strong> adverse temperatures.Toxic chemicals build up, <strong>and</strong> root growth can be mechanically impeded.This results in poor germination <strong>and</strong> emergence, poor plant growth<strong>and</strong> vigour, the need to resow, delays in sowing, root diseases, pestattack, <strong>and</strong> consequently lower crop yields. Plant stress induced bystructural degradation can also affect the quality of grain by changingthe amount <strong>and</strong> type of protein <strong>and</strong> starch formed, <strong>and</strong> the enzymicpotential. These affect the amount of fermentable carbohydrate <strong>and</strong>the malting potential of barley, <strong>and</strong> the baking quality of wheat.40 VISUAL SOIL ASSESSMENT: Volume 1