Some soils could take even more.The claims for biochar are not supported by all, however.
Near the Mekong, a high salt content in some soils limits crop production, although salt deposits there are mined commercially.
Repeated plantings of the same crops have, however, exhausted some soils, and many fields have been converted to pasture land.
Some soils require deepening of the root zone to permit increased rate of water intake and improved storage.
Scientists have known for decades that trees and other plants absorb carbon dioxide as they grow and some soils do as well.
Attempts at desalination appear to have been successful, and some soils that were formerly saline are now used for rice cultivation.
Ms. Garcia's well water, like that of her neighbors, is laced with excessive nitrates, a pollutant associated with agriculture, septic systems and some soils.
On some soils, the German Nature and Biodiversity Conservation Union estimates: "growing corn releases 700 grams of carbon dioxide into the atmosphere for every kilowatt hour of energy it produces.
Humic substances are the organic products of plant decay, which are also responsible for the brown colour of some soils and for the tealike colour of some swamp and lake waters.
In southwestern Russia, in portions of the Transcaucasus region, and especially in Ukraine, some soils that have been formed in areas of grass steppe are chernozems (black earths)—deep, friable, humus-rich, and renowned for their fertility.
Water and nutrient holding capacity can be improved in some soils.
