2. Long term effect of fertilization on soil health -PME
and LTFE
BY: B.SUBHASH
3. FERTILIZERS
• Fertilizers are chemical substances supplied to the crops to increase their productivity.
• These are used by the farmers daily to increase the crop yield.
• The fertilizers contain the essential nutrients required by the plants, including nitrogen, potassium, and
phosphorus.
• Fertilizers are used daily by farmers and families to help crops and gardens grow.
• Whether for a small garden of flowers and plants, or a large farm with thousands of acres of crops, a
wide range of fertilizers have been developed to help different crops grow in different soil and weather
conditions.
4. SOIL FERTILIZATION
• Fertilization is supplementing the existing soil with additional, needed nutrients. (OR)
• Fertilization is creating optimum conditions for the soil following which the crop can grow on the basis of
natural principles.
• Fertilizing wisely increases yield, quality (nitrogen content and digestibility), and profits.
5. ADVANTAGES OF SOIL
FERTILIZATION
• It increases crop yield and improves poor quality land.
• Manure improves soil texture, recycles nitrogen and introduces essential bacteria.
• Pasture is improved so animals fatten up quicker.
• Once marshland is drained, fertilizers can help reclaim that land for pasture.
6. DIS-ADVANTAGES OF SOIL
FERTILIZATION
1.They get washed away by water easily and cause pollution.
2.They harm the microbes present in soil.
3. They reduce soil fertility.
4.They are expensive.
5.They provide only short term benefits.
6. They change the nature of soil, making it either too acidic or too alkaline.
Examples: Urea, Ammonium Phosphate,etc.,
7. Long term effect of fertilization on soil health
• Long-term fertilization can remarkably increase soil organic carbon(SOC) and available nutrients, especially
in NPKM treatment.
• However, it also clearly decrease the soil C/N ratio and pH due to the continuous excessive application of N
fertilizers.
• Intensive cropping with continuous application of only inorganic fertilizers at high doses and indiscriminate
use of agrochemicals on soils has resulted in declining yield trend and multi-nutrient deficiencies in many
soils.
• Fertilization applied in long-term farming systems exerts a crucial influence on soil organism diversity and
soil properties.
8. • Use of mineral or organic fertilizers in agriculture increases inputs of nutrients to soils, and the form in which the
nutrients are applied and their fate in the soil-plant system determine the over all effects on soil pH.
• Macronutrients (N, P
,K) have the major effects on pH as they are added in much larger quantities to soil than
micronutrients.
• All the major fertilizer nutrients, nitrogen is the main nutrient affecting soil pH, and soils can become more acidic
or more alkaline depending on the type of nitrogen fertilizer used.
• Nitrate-based products are the least acidifying of the nitrogen fertilizers, while ammonium-based products have
the greatest potential to acidify soil.
• Potassium fertilizers have little or no effect on soil pH.
9. There are 2 methods to overcome from long term effects of fertilization
of soil health.
They are as follows:
Permanent manurial trials ( PME) &
Long term fertilizer experiments (LTFE)
10. Permanent manurial trials ( PME)
OBJECTIVE: To study changes in Soil Quality
Permanent Manurial Experiments
• Started at Rothamsted, England by Sir J.B. Lawes & J.H. Gilbert during 1843
• Started as agronomic experiment to determine the nutrient requirement ofcrops
• Eight of these experiments are still in progress.
• Provide data on considerable agronomic, ecological, environmental and scientific value
11. Long term fertilizer experiments (LTFE)
Objectives
• To study the effect of continuous application of plant nutrients, singly and in combination, in organic
and inorganic forms including secondary and micronutrient elements (as per the need) on crop yield,
nutrient composition and uptake in multiple cropping systems.
• To work out the amount of nutrient removal by the crops.
• To investigate the effect of intensive use of biocidal chemicals (weedicides and pesticides) on the
buildup of residues and soil productivity.
• To identify soil indicator and for assessing soil quality and impact of changing climate on soil
productivity.
• Impact of changing climate on soil health.
12. HISTORY
• In the beginning of 20th century, based on Rothamsted model, a series of manurial
experiments were established in India.
• Introduction of high yielding varieties, irrigation and high analysis fertilizer
accelerated the mining of nutrient other than supplied eternally from soil.
• To sustain the productivity it was essential to maintain the supply of nutrient. Since
large amount of nutrient has to be applied to soil in chemical form which may have
impact on soil properties and soil productivity in long term.
• Therefore, to study the impact of chemical fertilizer on productivity and soil quality,
the Indian Council of Agricultural Research decided to launch the “All India
Coordinated Research Project on Long-Term Fertilizer Experiments (AICRP-LTFE)”
in September 1972 at 11 centres.
13. • The work carried out at different centers of LTFE was reviewed by QRT during 1997 and recommended to
enlarge the mandate and objectives of the project and changed its title as AICRP on “Long-term fertilizer
experiments to study changes in soil quality, crop productivity and sustainability”.
• The purpose of conducting long term fertilizer experiments at fixed sites in different agro-ecological zones
(AEZ) with important cropping systems was not only to monitor the changes in soil properties and yield
responses and soil environment due to continuous application of plant nutrient inputs through fertilizers and
organic sources, but also to help in synthesizing the strategies and policies for rational use and management of
fertilizers to improve soil quality and to minimize environment degradation.
• Thus the thrust of All India Coordinated Research Project (AICRP) is on productivity, sustainability
andenvironment safety.
14. Crop response to fertilizer NPK
The salient findings generated from finger millet -
maize - cowpea sequence
continuously to evaluate the effect of single nutrients,
nutrient combinations with or without
farm yard manure
15. • Continuous application of nitrogenous fertilizers alone adversely affected the soil productivity resulting in drastic
reduction in yield to an extent of 75 - 80% in finger millet, maize and cowpea due to phosphorus becoming the
limiting nutrient.
• There was a spectacular improvement in crop yields when N and P were applied together as compared to N
alone.
• The increase in crop yields due to the integrated use of N and P varied from 40 to 80 per cent.
• There was generally a reduction in yield in the recent times in hand weeded plots indicating the ineffectiveness
of hand weeding in controlling the weeds which compete with the crop plants for nutrients.
16. Addition of ZnSO4 to maize crop in the sequence did not bring about any significant improvement in the yield
of maize, cowpea or finger millet crops suggesting no response to the application of zinc.
Continuous exclusion of S from the fertilizer schedule had no adverse effect on the yields of finger millet,
maize and cowpea crops but there was a yield reduction in the recent years.
The increase in yield over control and 100% N treatment was to the extent of about 173 -271 per cent
and 114 - 170 per cent, respectively, over optimum NPK level in all the crops.
17. Build up and depletion of nutrients
The soil N reserve as reflected by total N measurements was found to build up
over years
with all the nutrient input systems excepting no manuring and sub-optimal
level of
fertilizer NPK whereas, N availability in soil was maintained without
appreciable change
over years with all the nutrient input systems.
The soil K reserve as reflected in total K
measurements was found to decline slowly, with
intensive cropping irrespective of nutrient input
systems followed. Similar is the case
with K availability in the soil.
18. There was a continuous depletion of available K over
the years in all the treatments irrespective of fertilizer
K addition .
Application of NPK+FYM resulted in marginal to
moderate improvement in diethylenetriamine penta
acetic acid(DTPA) extractable Zn over the NPK
treatment there by indicating the efficacy of organic
manures in meeting micro nutrients requirements of
the crops.
Application of 100% NPK + FYM increased the DTPA
extractable iron, copper and manganese contents.
19. Soil organic matter and its maintenance
• Balanced use of NPK fertilizer either maintained or
slightly enhanced the soil organic carbon (SOC)
level over the initial values.
• Beneficial effect of FYM in improving the organic
carbon over control, N, NP and NPK fertilizer was
observed.
• About 66.6 per cent increase in organic C content
over control was noticed with the integrated use of
FYM and fertilizers.
20. The maximum activity of enzyme phosphatase was
observed for the integrated application of 100% NPK +
FYM rather than for application of 100% NPK alone.
Water soluble organic carbon and water soluble
carbohydrates were found to be highest in the
treatment which has been continuously receiving FYM
@10 t ha-1 along with 100%
NPK.
21. Nutrient use efficiency
Fertilizer N efficiency was poor where N alone was
applied, P addition improved the N efficiency , but
inclusion of K did not improve it. Fertilizer K efficiency
in Finger millet and maize declined with increasing
amounts of NPK.
• The partial factor productivity of N was very low in
all the crops.
• But NP application increased the partial factor
productivity by about 10 times in finger millet, 3
times in maize and two times in cowpea over
application of N alone.
