L3 Soil Science Fertilization of Soils hlayiso.com

NATIONAL CERTIFICATE (VOCATIONAL) PRIMARY AGRICULTURE SUBJECT: SOIL SCIENCE LEVEL: 3 LECTURER: MOKHEHLE TK Downloaded from hlayiso.com 1

TOPIC: FERTILIZATION OF SOILS SUBJECT OUTCOME: EXPLAIN WHAT IS MEANT BY PROBLEM SOILS AND EXPLAIN THEIR PROPERTIES LEARNING OUTCOME: DESCRIBE THE TREATMENT OF ACIDIC, ALKALINE AND SODIC SOILS AND THEIR MANAGEMENT. Downloaded from hlayiso.com 2

TYPES OF PROBLEM SOILS AND THEIR TREATMENT ACIDIC SOILS Characteristics: o pH is less than 6.5 o These soils are open textured with high massive Structure. o Low in Ca, Mg with negligible amount of soluble salts. o These soils appear as brown or reddish brown, sandy loams or sands. Amelioration (Treatment): o Lime as reclaiming agent: Lime is added to neutralize acidity and to increase the pH, availability of nutrients be increased. o Basic slag obtained from Iron and steel industry can be substituted for lime. o Ammonium sulphate and Ammonium chloride should not be applied to acid soils but urea can be applied. o Calcium Ammonium Nitrate (CAN) is suitable to acidic soils. o Any citrate soluble phosphate fertilizer is good source of phosphorous for acidic soils. o Dicalcium phosphate (DCP), Tricalcium phosphate (TCP) Potassium sulphate is a suitable source of ‘K’ for acidic soils. Downloaded from hlayiso.com 3

ACIDIC RECLAMATION ILLUSTRATED. Downloaded from hlayiso.com 4

TYPES OF PROBLEM SOILS AND THEIR TREATMENT CONTINUES.. ALKALINE SOILS Characteristics: o Alkaline soil has soil pH of more than 8.5 o EC (Exchange Capacity) is less than 4.0 m.mhos/cm o ESP (exchangeable sodium per cent) is more than 15 o It has black colour that why it is also called as Black alkali. Amelioration (Treatment): The process of amelioration consists of two steps: • To convert exchangeable sodium into water soluble form. • To leach out the soluble sodium from the field. Amendments used for reclamation of Alkali soils. o Gypsum - It is slightly soluble in water. So it should be applied well in advance. o Sulphur present in pyrites causes decrease in pH of soil due to formation of H2SO4. o Application of sulphur. o Application of molasses. o Drainage channels must be arranged around the field. o Downloaded from hlayiso.com Growing the green manure crops and incorporates in the field. 5

EFFECTS OF ACIDITY AND ALKALINITY ON CROP GROWTH. Downloaded from hlayiso.com 6

TYPES OF PROBLEM SOILS AND THEIR TREATMENT CONTINUES.. SALINE-SODIC SOILS Characteristics o Saline soil has soil pH of less than 8.5 o ESP (exchangeable sodium per cent) is less than 15. o Dominated by sulphate and chloride ions and low in exchangeable sodium. o Flocculation due to excess soluble salts. o High osmotic pressure of soil solution. o It has white colour that why it is also called as White alkali. Amelioration (Treatment): o Salts are to be leached below the root zone and not allowed to come up. o The smaller plots should be bounded to hold irrigation water. o Separate irrigation and drainage channels are to be provided for each plot. o The excess water with dissolved salts is to be removed into the drainage channels. o Green manure crops can be grown up to flowering stage and incorporated into the soil. o Super phosphate. Ammonium sulphate or Urea can be applied in the last puddle. Downloaded from hlayiso.com o Grow salt tolerant crops like sugar beet, tomato, beet root, barley etc. 7

EFFECTS OF SALINE-SODIC SOILS ON PLANT GROWTH. Downloaded from hlayiso.com 8

RECAP.. WHAT HAVE WE LEARNT:… o HOW ACIDIC,ALKALINE AND SALINE-SODIC SOILS CAN BE TREATED OR RECLAIMED. o IDENTIFICATION OF PROBLEM SOILS WITH THEIR CHARACTERISTICS o INFLUENCE OF PROBLEM SOILS ON CROP GROWTH AND TOTAL PRODUCTION. NEXT LESSON ON: PROCEDURES OF SAMPLE COLLECTION FROM THE FIELD. STAY SAFE AND STUDY REGULARLY. THANK YOU.. Downloaded from hlayiso.com 9