Santhosh
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Transcript of Santhosh
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Soil fertility evaluation
Dr. Santhosh C. GVHSS BOYSKUNNAMKULAMTHRISSUR
Introduction
Optimum productivity of any cropping system depends on adequate supply of plant nutrients
Continued removal of nutrients will increase the potential for future nutrient related plant stress and yield loss
Proper rate of plant nutrients is determined by nutrient requirement of the crop and nutrient supplying power of the soil
Value of soil and plant analysis depends on careful sampling and analysis
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Nutrient deficiency symptoms of plants
Analysis of tissue from plants growing on the soil
Biological tests
Soil analysis
Techniques to assess soil fertility
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Nutrient – deficiency symptoms in plants
Growing plants are integrators of all growth factors
Lack of particular nutrient will produce characteristic symptoms
Classification of nutrient deficiency symptoms
•Complete crop failure at seedling stage•Severe stunting •Specific leaf symptoms•Delayed or abnormal maturity•Poor quality of crops
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Nutrient deficiency in plants
Hidden hunger
• Refers to a situation in which a crop needs more of a given nutrient yet has shown no deficiency symptoms
• A term used to describe a plant that shows no obvious symptoms yet the nutrient content is not sufficient to give the top yield
Plant analysis
• Fresh tissue test in field
• Tissue analysis in lab
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Concept of plant analysis
Amount of given nutrient in plant is directly proportional to availability of nutrient in soil
Why tissue tests and plant analyses?
To aid in determining the nutrient supplying power of soil
To help in identification of nutrient deficiency symptoms
To aid in determining the effect of fertility treatment
To study the relationship between nutrient status of plants and crop performance
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Tissue tests
These semi quantitative tests are intended for verification of deficiency symptoms
General methods
Chopped plant parts will be treated with extractants and intensity of colour developed will be compared with standards
Plant tissue will be squeezed with pliers to transfer the plant sap to filter paper
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Plant parts tested
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Parts that will give the best indication of nutritional status
Conductive tissue of the latest mature leaf
Time of testing
Most critical stage is at bloom stage of from bloom to early fruiting stage
In corn, the leaf opposite and just below the uppermost ear at silking is sampled
Well suited for forage crops
Interpretation
General performance and vigour of plant Levels of other nutrients in plants Incidence of insects and pests Soil conditions like moisture, aeration etc. Climatic conditions Time of day
Total analysis
Plant materials are ground and analysed by digesting or ashing.
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Critical nutrient concentration (CNC)
• CNC is located in that portion of the curve where the plant nutrient concentration changes from deficient to adequate
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Crop When to sample
Part of plant
Rice Seedling stage All the above ground portions
Prior to heading
Four upper most leaves
Cucumber Before fruit set Mature leaf near the base of stem
Leaf crops Mid growth stage
Youngest mature leaf
Balance of nutrients
One of the problem in the interpretation of plant analyses is that of balance among nutrients
Ratios of nutrients in plant tissues are used to study nutrient balance in crops
Eg:- N/S, K/Mg, K/Ca, Ca+ Mg/K, N/P
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DIAGNOSIS AND RECOMMENDATION INTEGRATED SYSTEM (DRIS)
A system that identifies all the nutritional factors limiting crop production and thus increases the chance of obtaining high crop yields by improving fertilizer recommendations
Requirements of DRIS
All factors suspected of having an effect on crop yield must be identified
The relationship between these factors and yield must be described Calibrated norms must be established Recommendations suited to a particular set of conditions must be
continually refined
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Establishment of DRIS norms
A survey to obtain data required to establish DRIS norms
Random selection of sites representing the production area
Conduct plant and soil analyses
Record all parameters related directly or indirectly to yield
Entire population of observations are divided into two populations
Each nutrient in plant is expressed in as many ways as possible
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Chlorophyll meter
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Provide an indication of leaf nitrogen status
Crop logging
A graphical record of the progress of crop containing series of chemical and physical measurements
Measurements indicating general conditions of plant and suggest changes in managements
CNC approach is used
Leaf sheath is sampled for analysis
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Biological tests
Strip tests of farmer’s field
Neubauer seedling method – based on uptake of nutrients by a large nos. of plants on a small quantity of soil in short time
Microbiological methods – growth of azetobacter or aspergillus niger reflects nutrient deficiency in soil
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Deficiency Crop
Nitrogen Maize , Sorghum ,Leguminous plants
Phosphorus Tomato ,Maize, Lucerne, Cereals, Duranta
PotassiumMaize, Lucerne , Cotton, Potatoes, Banana, Cucurbits
Sulpur
Lucerne , Clover , Cereals, Tea
Zinc Maize, Tomatoes , Potatoes, Beans, Citrus
Copper Citrus
Iron
Ornamental plants, Ixora, Acacia, Eucalyptus, Gooseberry, Securmanis
Boron Lucerne, Coconut, Guava
Manganese Citrus
Molybdenum Cauliflower, Cabbage
Indicator plants
Soil fertility card
Selection of Area:-
Extent of rice cultivation was used as one of the criteria for selection of area under the project.
Representative areas from three major agro ecological zones
in the district were also included. Thus 42 Panchayaths having more than 25% geographical area under rice representing three agro ecological zones in the district were selected for sampling.
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Soil sampling
Detailed soil survey and surface soil sample collection were carried out by NBSS & LUP in 12 Panchayaths and by KSSO in the remaining 30 Panchayaths. Surface soil Samples were collected from plots under each survey number. Collected samples were handed over by these agencies to RARS, Pattambi for processing and estimation of available nutrients.
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Soil pollution
Pollution of earth’s natural land surface by industrial,commercial, domestic and agricultural activities
Introduction of substances into the soil, resulting in a change of soil quality, which is likely to affect the normal use of soil or endangering public health and living environment.
Soil contaminants spilled onto the surface through many activities.
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Causes of soil pollution
Accidental Spills
Acid rain (air pollution)
Intensive farming
Nuclear wastes
Industrial Accidents
Landfill and illegal dumping
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Land Erosion
Agricultural practices such as application pesticides,herbicides and fertilizers
Mining and other industries
Oil and fuel dumping
Buried wastes
Disposal of coal ash
Disposal of ammunitions and agents of war.
Drainage of contaminated surface water into the soil
Electronic waste
Industrial wastes
Fly ash Effluents ie. Organic compounds and inorganic complexes
Urban wastes
Commercial and domestic wastes Solid wastes gargage and plastic, metallic containers
Radioactive pollutants
Nuclear wastes Thorium, uranium, heavy water (Sr-90, Cs-137) causing gama
radiation
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Agricultural practices
Fertilizers and pesticides Toxic metals- lead, arsenic, mercury, cobalt, cadmium etc.
Acid rain
Air pollution- motor vehicle and factory emissions
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Control of soil pollution
Principal remedial strategies
Aeration
Bioremediation
Extraction of ground water or soil vapours
Excavation of soil
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