Soil-Plant Nutrient Cycling and Environmental Quality, SOIL5813

Homework #1

Due: February 4, 2000

Name:_______________

1.     Work by Wallace et al. (1990) documents that CO₂ levels have increased from 260 to 340 ppm over the past 150 years.  The increase in CO₂ as a result of decreased soil organic C (due to cultivation) was estimated to account for 6 to 25% of the 80 ppm change.  Atmospheric CO₂ levels are now 360 ppm (100 ppm change in the last 150 years).

2.     Stating all assumptions, calculate

1. The increased land area grown to cereals (average of 4.3 Mg/ha for Maize, 2.7 Mg/ha for Wheat and 3.8 Mg/ha for Rice) needed to sequester all of the 3 GT C that remains in the atmosphere
2. The increased land area seeded to trees (temperate climate forests) needed to sequester all of the 3 GT C that remains in the atmosphere
3. The increased land area devoted to pastures/range needed to sequester all of the 3 GT C that remains in the atmosphere

* note:  if the 3 GT number cited by Wallace can be updated via another reference, please do so.

Agroforestry, if adopted at a rate of ___, could reduce annual C emmissions by ____

ANSWER: (excel file)