The nutrients that a plant needs to grow naturally go back into the soil for the next plant to use. Soil productivity depends on the Soil organic matter. This is things that decompose into the soil . Things like leaves, twigs, animal skin, and plant skin. These organic matters loosen the soil making it easier for pores to open and keep air for plants and underground animals to breathe.
Soil degradation is something that absolutely happens do to human interaction. The most important thing it does soil's ability to support those that depend on it. Soil degradation affects crop production especially making it difficult to grow crops. Salinization occurs when n soil is irrigated repeatedly. Salinization is when the is left in the soil from the irrigation water and it can make it difficult for plants to soak up the water that it needs to grow.
"K-12 Soil Science Teacher Resources." Chemistry. Web. 10 Dec. 2014. <http://www.soils4teachers.org/chemistry>.
"Soil Chemical Properties." Soil Chemical Properties. Web. 10 Dec. 2014. <http://soils.tfrec.wsu.edu/mg/chemical.htm>.
Brown, Catrina, and Mike Ford. "Environmental Chemistry: Option E." Chemistry: Higher Level : Developed Specifically for Thr IB Diploma. Oxford: Heinemann :, 2009. Print.