Santhosh

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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Santhosh

Education

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