What are the main forms of soil degradation and how can they be mitigated?

• A. Soil erosion and nutrient depletion; mitigations include applying fertilizer.
• B. Soil salinization due to irrigation; mitigations include drainage and proper irrigation scheduling.
• C. Soil compaction from heavy machinery; mitigations include reduced tillage and organic matter.
• D. Erosion, compaction, salinization, acidity/alkalinity; mitigations include cover crops, reduced tillage, organic matter, drip irrigation, liming.

Answer: (D)

Soil degradation involves several interrelated problems that degrade soil structure, fertility, and function. The best approach to mitigation is a set of practices that addresses multiple issues at once, rather than focusing on a single problem.

Erosion removes the nutrient-rich topsoil and reduces water-holding capacity, so practices that protect the soil surface are crucial. Cover crops shade and protect the soil, reduce runoff, and add organic matter that helps binding soil particles. Reduced tillage or no-till preserves soil structure and porosity, which helps resist erosion. Adding organic matter builds crumb structure and improves stability, making soil less prone to washing or blowing away.

Soil compaction tightens the soil, reduces pore space, slows infiltration, and hinders root growth. Practices that loosen and maintain soil structure—reduced tillage along with adding organic matter—help create spaces for air and water, improving drainage and root penetration. Thoughtful management of field traffic also minimizes compaction.

Salinization from irrigation water concentrates salts in the root zone, harming plant uptake of water and nutrients. Mitigation includes improving drainage to remove salts and using irrigation schedules that promote leaching of salts when appropriate. Drip irrigation minimizes water loss and evaporation, reducing salt buildup at the soil surface and around the root zone.

Soil acidity or alkalinity affects nutrient availability and microbial activity. Liming neutralizes overly acidic soils (and can adjust very alkaline soils toward a more favorable pH), making nutrients more available to plants.

The listed mitigations—cover crops, reduced tillage, organic matter, drip irrigation, and liming—address these issues in a complementary way, targeting erosion, compaction, salinization, and pH imbalances together. That’s why this option is the most complete and effective.