FERTILIZER USE EFFICIENCY IN SALT AFFECTED SOILS A REVIEW

2. FERTILIZER USE EFFICIENCY IN SALT AFFECTED SOILS A REVIEW Dr. SHAHZADA MUNAWAR MEHDI DIRECTOR SOIL FERTILITY RESEARCH INSTITUTE, LAHORE

3. GLOBAL SCENARIO OF THE PROBLOM Soil salinity and sodicity - global problem, exists in six continents and nearly 100 countries including Pakistan. Major countries - Argentina, Australia, Egypt, Iran, Pakistan, USA, Russia, India, China, Thailand and South Africa.

5. SOIL SALINITY/SODICITY PROBLEM IN PROVINCES OF PAKISTAN(m ha)

6. Salt-Affected Area (m ha) of Punjab, Pakistan Source: Ahmad & Chaudhry, 2004

7. Source: Punjab Development Statistics, 2006

8. Source: Punjab Development Statistics, 2011

9. Salinity/sodicity: 6.68 m ha • 60 % are saline-sodic in Pakistan, • 84 % are saline-sodic in Punjab • (Khan, 1998)

10. CROPS / PLANTS TOLERANCE WITH RESPECT TO SALINITY AND SODICITY

11. Field crops

14. Forages

16. Vegetables

18. Medicinal plants

19. NUTRITIONAL ASPECTS OF SALT AFFECTED SOILS • Availability of plant nutrients is affected adversely in salt affected soils and their productivity is decreased resultantly. • The main reasons for depletion in fertility of such soils are as under:- • Excess of certain ions like Na, CO3 and HCO3 suppress the availability of other like Ca, K, P, Zn, Mn, Fe and B. technically, it is called antagonistic effect. • An increase in soil pH, especially in sodic soils decreases the overall availability of phosphorus and micronutrients. • In salt affected soils microbiological activity is curtailed to a great extent. • During the reclamation process, leaching of salts is also accompanied by leaching of nutrients. • Nutrient uptake by plants in salt affected soils is also reduced due to decreased water uptake because of physiological unavailability of the latter.

20. NITROGEN • Nitrogenous fertilizer play important role in utilizing the salt affected soils for improving crop yield because • 1. These soils are deficient in nitrogen. • 2. Low N and organic matter contents • 3. Reduced microbial population • 4. Rate of mineralization of nitrogen is slow down. Salinity level (ECe) above 10 dS m-1 is harmful • Nitrogen absorption by plants increase up to moderate salinity value (6 dS m-1) and then decreases at higher salinity values and ESP of soil. • The rate of conversion of one form of nitrogen to other forms is quite slow e.g. hydrolysis of urea to ammonium N was much slow down with increase in soil pH.

21. 7. Low enzymatic activity in saline soils. 8. Chloride reduces the rate of nitrification when present between 0.5- 1.0 percent. 9. Ammonium volatilization loss from applied nitrogen increases with increase in pH/alkalinity of soil 10. 20-25 percent over dose of nitrogen fertilizers

22. PHOSPHORUS • Chemistryof phosphorus is more complex in salt affected as compared to • normal soils. • The availability of P is decreased in sodic soilduring reclamation. • 2. The availability of P in saline soil may decrease, increase or remain unchanged depending on the nature and degree of salinity. • 3. Salts which change pH show more changes in the solubility of phosphates in soils. • Barren sodic soils have high amounts of Olsen extractable P and categorized as adequate in available P. • Amount of water soluble P increase with soil pH above 9.0. • The availability of phosphorus increases up to moderate salinity (ECe 6 dS m-1)

23. 7. In sodic soils, there is a tendency for increase of Ca-P form with increase in ESP and decrease in Al-P 8. In highly saline sodic soils about 10-15 percent more P is to be added and special care is to be taken for calcareous soils. 9.Phosphorus absorption by plants is generally reduced with increase in salinity and ESP of soil. 10. P uptake by plants increases up to moderate salinity (ECe 6 dS m-1) and ESP (30-35) levels.

24. Potassium • 1. Increase in soil salinity depresses the K uptake by plant while Na uptake increases. • In sodic soil Na increases and those of Ca, Mg and K decreases.

25. MICRONUTRIENTS • High pH, high CaCO3, high ESP, low organic matter content and high amount of soluble salts are the major factors responsible for micronutrients deficiencies in salt affected soils. • Among the micronutrients, Zn deficiency is wide spread in sodic soils. Other micronutrients like Fe, Mn and Cu are also precipitated as their hydroxides or carbonates in highly alkaline range and may show their deficiency. • In many areas particularly under poorly drained condition in medium and fine textured soil B has been reported to be present in toxic amounts.

26. Low nutrient use efficiency

27. Field experiments Results

28. RESPONSE OF RICE LINE PB-95 TO DIFFERENT NPK LEVELS Original soil analyses pHs 8.60 ECe (dS m-1) 4.72 SAR (mmol L-1)1/2 26.28 O.M. (%) 0.42 Available P (mg kg-1) 5.18 Extractable K (mg kg-1) 86.0

33. RESPONSE OF WHEAT TO POTASSIUM APPLICATION IN SALT AFFECTED SOILS. Treatments: T1: 140-110-0 kg NPK ha-1 T2: 140-110-30 kg NPK ha-1 T3: 140-110-60 kg NPK ha-1 T4: 140-110-90 kg NPK ha-1 T5: 140-110-120 kg NPK ha-1

34. Pre-sowing Soil Analysis: ECe: 5.28 d Sm-1 pHs: 8.57 SAR: 29.80 OM: 0.36% Avail. P: 5.32 mg kg-1 Ex. K: 114 mg kg-1

36. RESPONSE OF RICE TO POTASSIUM APPLICATION IN SALT AFFECTED SOILS. Treatments: T1: 110-90-0 kg NPK ha-1 T2: 110-90-25 kg NPK ha-1 T3: 110-90-50 kg NPK ha-1 T4: 110-90-75 kg NPK ha-1 T5: 110-90-100 kg NPK ha-1

37. Pre-sowing Soil Analysis: ECe: 6.10 d Sm-1 pHs: 8.75 SAR: 37.56 OM: 0.28% Avail. P: 5.90 mg kg-1 Ex. K: 110 mg kg-1

39. RESPONSE OF WHEAT TO BORON APPLICATION IN SALT AFFECTED SOIL

40. PRE-SOWINGSOIL ANALYSIS

41. Effect of different rates of boron on grain and straw yield of wheat

43. Post Harvest soil analysis

44. THANKS