Soil Fertility | Biology for JAMB PDF Download

Loss of soil fertility

Soil fertility refers to the ability of the soil to support plant growth and provide essential nutrients. Several factors can contribute to the loss of soil fertility, including:

• Loss of inorganic matter: Continuous farming without adequate replenishment of nutrients can deplete the soil of essential minerals and elements necessary for plant growth.
• Compaction: Heavy machinery, excessive foot traffic, and inappropriate land management practices can lead to soil compaction, reducing pore spaces and limiting root penetration, water infiltration, and nutrient absorption.
• Leaching: Excessive rainfall or over-irrigation can cause the leaching of nutrients, particularly water-soluble minerals like nitrates and phosphates, which are essential for plant growth.
• Erosion of topsoil: Poor land management practices such as improper plowing, deforestation, and unsustainable farming techniques can result in the erosion of the topsoil layer. Topsoil erosion leads to the loss of organic matter and essential nutrients.
• Repeated cropping with one variety: Monocropping, or the continuous cultivation of the same crop on the same land, can deplete specific nutrients from the soil, leaving it deficient and reducing overall fertility.

Renewal and maintenance of soil fertility

To enhance soil conservation and maintain soil fertility, various practices can be applied. These include:

• Contour ridging: Creating ridges across slopes helps to reduce water runoff, control erosion, and conserve soil moisture.
• Terracing: Constructing terraces on steep slopes helps to prevent soil erosion, as they form level platforms that retain water and reduce the velocity of runoff.
• Mulching: Applying organic materials, such as straw, leaves, or compost, as a protective layer on the soil surface helps to reduce water evaporation, control weeds, and enhance nutrient cycling.
• Poly-cropping and strip-cropping: Planting multiple crops together in the same field (poly-cropping) or alternating different crops in adjacent strips (strip-cropping) helps to reduce pest and disease outbreaks and improve nutrient availability.
• Use of organic and inorganic fertilizers: Organic fertilizers, such as compost and manure, enrich the soil with organic matter and nutrients. Inorganic fertilizers, such as nitrogen, phosphorus, and potassium compounds, provide specific nutrients that may be deficient in the soil.
• Crop rotation: Rotating different crops in a planned sequence helps to break pest and disease cycles, improve soil structure, and balance nutrient demands.
• Shifting cultivation: This traditional farming practice involves clearing a patch of land, cultivating it for a few years, and then moving on to a new area. The abandoned land is left fallow, allowing it to regenerate and restore fertility.