SOIL FERTILITY MANAGEMENT AND DESCRIBE NUTRIENT DEFICIENCY SYMPTOMS IN PLANT ACCORDING TO GOOD AGRICULTURAL PRACTISE.

Soil fertility

•Soil fertility – the ability of soil to supply nutrient for  plant growth.

• The soil is a storehouse of plant nutrients, stored in many forms, some very available to plant and some less so.

Plant nutrient

Plant nutrient – the essential elements needed for plant growth.

Plants absorb at least 90 different elements ; only a few are needed for plant growth.

Primary nutrient deficiency symptoms

NITROGEN ( N )

•                                               Stunted and spindly.
• Yellow , yellowish green or light green in color in foliage ( chlorosis )
• Order leaves affected first , starting at the tip and moves along the middle of the leaf.

Primary nutrient deficiency symptoms

Phosphorus ( P )

ØStunted growth

ØVery dark green color.

ØPurple leaves or portions of leaves in advanced stages.

ØOlder leaves affected first.

Primary nutrient deficiency symptoms

POTASSIUM (K )

§Shorter plants.

§Bronzing or browning of leaf color.

§Lodging ( bending of the stem ) occurs.

§Leaves show yellow to brown coloring along leaf margins followed by complete browning.

SECONDARY NUTRIENT DEFICIENCY SYMPTOMS

SULFUR (S)

vYoung plants have stunted appearance.

vLeaves have a light-green to yellow coloring.

vStems are thin and spindly.

vSulfur deficiency symptoms are similar in appearance to nitrogen deficiency.

SECONDARY NUTRIENT DEFICIENCY SYMPTOMS

MAGNESIUM ( Mg )

üLeaf parts between veins show a whitish colour.

üLeaf tissue becomes yellow , veins remain green ( interveinal chlorosis ).

üLeaves curl upward along the margins.

FACTORS AFFECTING NUTRIENT AVAILABILITY

CEC – Smaller amounts of fertilizer , applied more often , are needed in low CEC soils to prevent leaching losses , while larger amounts may be applied less frequently in high CEC soils.

ü   Base saturation – Most crops grow best at a base saturation of > 80%.

ü   Leaching – Anions ( negatively charged ions such as NO³⁻ ) usually leach more readily than cations.

ü   Soil Ph – influences nutrient solubility.