Testing of Soil is done to determine the presence of nutrients in the soil and characteristics of the soil. Soil testing is very important in Agriculture and crop production as it tells us about the soil and available nutrient in the soil.
Soil testing is not only tells us about the nutrient available in the soil but also its characteristics’ such as pH level. By soil testing we can determine soil fertility status, toxicity and traces of contaminated chemicals, and deficiency of certain nutrients and minerals in the soil.
Every year Millions of Dollars spent and wasted by farmers all over the world due to indiscriminate use of fertilizers. Due to non availability of soil testing, farmers keep on putting those fertilizers in the soil which was already available in the soil. Not only this, farmers keep on using unnecessary fertilizers but forget to provide fertilizers and other nutrients which are really deficient in the field.
Soil testing is needed to avoid nutrient balance. Plants require 16 essential nutrients and out of these 16 essential nutrients, 13 are absorbed by plants from soil.
These 16 essential nutrients are carbon, Hydrogen, oxygen, Nitrogen, Phosphorous, potassium, calcium, magnesium, sulfur, Boron, chlorine, copper, iron, manganese, molybdenum and zinc.
Plants take Carbon, Hydrogen and oxygen from air and for other nutrients it has to depend on soil.
It is very necessary that balance of all these nutrients and pH status of soil to be maintained otherwise any imbalance of nutrients may results, interference of other nutrients availability to the plant, this may result decreasing quality and quantity of crop yield.
Soil testing is also important to monitor soil degradation and give inputs to make long run fertilizer policy.
Soil testing is usually done in soil testing laboratories. At present lot of new soil testing kits are available and with good training some basic soil testing can be done at field site.
Although some basic soil testing can be done at field but for extensive sol testing it is better to send soil sample to good soil testing laboratories.
Advantage of Soil Testing
1. Reduce cost of cultivation
After getting soil testing report, we can avoid unnecessary use of those nutrients which are already available in the soil, thereby reducing cost of growing crops.
2. Minimise nutrient deficiency
With soil testing report we can provide deficient nutrients and fertilizers in the soil.
3. Optimum Use of Inputs
With knowing soil testing report and requirement of nutrient in the soil for crops to be grown, we can calibrate our fertilizers programme.
4. Protection of Environment
Soil testing report will stop using of excess nutrients in the field, which will protect our environment.
5. Precise use of fertilizers and nutrient for targeted crop
Soil testing will let you know the quantity of available nutrients in the soil and by this report in your hand you can calculate the quantities of nutrient require for specific crop which you want to grow in your field.
6. Improved food security due to high yield with minimum cost
After knowing the results of soil testing reports you can take immediate action in this regard and provide optimum quantity of nutrients which will lead to good quality and quantity of crops.
Let’s talk about professional soil testing:
Soil Testing Phases:
1. Soil Sampling
2. Analysis of Soil Sample
3. Results and Data Interpretation
1. Soil Sampling
Soil sample should be taken at least one month before crop planting.
To take soil sample you will require following tools:
1. Soil tube
2. Screw auger
Spade should be used in “V” shape manner. In this method you should cut soil in “V” shaped at required depth and remove vertical slice.
To test soil, test laboratories required around 500 gm soil which should be a true representation of the field. For one hectare land, you should at least take 05 soil samples from different random places. Soil samples should be taken after digging soil 0-15 cm for general crops and 30 cm for orchard and deep rooted or problem soil.
Before digging soil for soil sample, you must remove organic debris and any other type of debris including any trash material.
Avoid taking sample from a place near to water channels and field paths. Before taking soil sample clear the soil from crop straw and stubble or any other material like manure.
After taking soil samples from different locations, these soil samples should be mixed thoroughly. After mixing it, take out 500 gm soil, which should be dried under shade. Now this soil sample should be transferred to polythene bag or clean cloth which does not have any traces of any other material.
Please put details of soil sample on container. Following details will be required to mention for the identification of soil sample:
2. Field Number
1. Address of location from where sample taken.
3. Cropping rotation followed in this soil
4. What source of irrigation available at the site.
5. Whether soil is water logged
6. What types of manure, fertilisers previously used in this field
7. What crops grown in this area
8. Any special observation about this field
Analysis of Soil Sample
Soil testing results give us details regarding plant available contents within sample for elements like N, P, K, Ph, Ca, Mg, S, Organic carbon and other micro nutrients like Zn, Br, Mn, Cu, Mo etc. Soil testing report also gives report regarding Soil pH, humic matter and exchangeable acidity in soil sample.
Soil sample reports show organic carbon (%), Available N, available P and available K.
If pH – 6.6 or lower indicate soil is acidic
pH – between 6.7 to 7.3 means soil is neutral soil
pH – Higher than 7.3 Means soil is basic
Soil test category can be categories as follows:
1. Critically Low
4. Above optimum
5. Critically High level
- Critically Low
At this level particular nutrient is at very low level which means it is directly affecting crop yield and nutrients require on urgent basis. There is high probability that crop response to this nutrient will be substantial.
- Low level
This means specific nutrient availability is not up to the mark and require additional nutrient.
- Optimum level
This is the most desirable test report which shows that nutrient is available at appropriate level. It is quite efficient economically and in most cases environment friendly.
- Above Optimum level
At this level availability of nutrients in the soil is considered more than adequate and if at this level more nutrient put in to the soil than it may have negative impact on crop yield & Quality of crops.
To get updated details regarding soil sampling laboratory in your country you can contact agricultural universities or agricultural Department in your area. Area specific soil testing lab can be searched on internet or visiting local agricultural offices / Departments. In India you may visit Indian government – farmer’s portal to get detailed information’s regarding laboratories all over the country.
In the end we would like to emphasise here that soil testing should be made mandatory all over the world and concerned governments should build infrastructure for soil sampling at local levels so that we can encourage optimum use of fertilizers to increase crop yield and quality of crops. It will be a significant step for removing hunger from our planet. It will also help us to avoid indiscriminate use of fertilisers, nutrients and chemicals which will save millions of dollar as well as safe our environment.