Reference no: EM132405085
In contrast to ecosystems that are not harvested (e.g., native forest, grasslands), wherein nutrient cycling is generally quite conservative, most agricultural ecosystems are net exporters of nutrients inherent in soil. Consider the following barley production system:
Soil contains 0.5% "available" Ca in the rooting zone to a depth of 50 cm.
Soil bulk density is 1.30 g/cm^3
Total plant production (above ground biomass) is 4000 kg/ha/yr (dry-weight basis).
Total grain yield is 2200 kg/ha/yr (dry-weight basis).
Ca content of the grain is 0.05%.
Ca content of the whole above ground plant is 1.5%.
1 ha = 10,000 m^2
a) If only the grain is removed from the field, how many years will the "available" Ca supply in the soil last (assuming yields don't decrease as Ca content decreases)?
b) If the entire barley plant is removed, how long will the Ca last (same assumption as above)?