Hi Balwant, do not forget pollutants that could contaminate your soil and sometimes sterilize it. So first, if organic products could be of interrest if not too concentrated, be sure that the charge in bacteria is not too important. Some of them could interfere with the normal flora of soil and then with plants. Secondly, be sure that your medium is not toxic because of waste of industry or other human activity (chemicals, drugs, heavy metals,..). Generally when there is no life in water be careful! By example, In France, We use a very simple system with salmo truta fishes as a biological detector because they like and need very clear and clean water to survive thus any pollution id rapidly detected by the death of these fishes.

It is difficult to give you advice about what to test because even good products could be poisonous if too concentrated of mixed with others. As written by Rushi, it is just possible to find advice about water and minerals needs for the plant you target to manage. At contrary, if you have knowledge of any source of pollution of the river or water table, you have first to test the presence of these pollutants. It is more simple and targeted.

I hope to have helped!

best regards

Aspects from my side & tropical experiences: 1. There are various analytical standards in respect to relevant parameters; easy to find in search-machines. 2. Coltan-mining areas / mining-areas general should be scrutinized with utmost care. 3. Do not underestimate the high potential to "re-fertilize" and re-level irrigation-soils with muddy / silty irrigation-waters from rivers after heavy downpours of rains. Egypt knows a fine story about that. 4. In Euphrat-area / salinity-/alkalinity complex contact ACSAD Damascus. 5. Check options of distributing organic / mineralic fertilizer by the inflowing waters. 6. Farmers along the rivers of your area of interest using water for irrigation since decades are good indicators & resource-persons for adequate water-quality. 7. Never forget that the water you are taking from a river may cause poverty & thirst & conflict & pollution further downstream !!! 8. The seasonal water-quantities need to be established with high attention.

Flowing waters in ideal situation/conditions are supposed to be the best source for irrigation of crops. Whereas in reality river waters at least in India are highly polluted since they, are used as waste disposal avenues with impunity. Therefore, it is necessary to test the waters for their quality in Soil Test Laboratories spread all over India to test waters and interpret the results for their suitability for agricultural crop production. 

Your question is very general and many parts of the world river water is used for agriculture. As suggested by others, its better to know the quality of a particular river water (minerals and pollutants) at different locations prior to use.

dear ruchi, Mamnet, Biesen, Reddy and Cerian thank you fir your valuble information. i jst want to know if i mesure the pollutent in river water as aspect of agriculture puposes we mesure sodium absorption ratio, sodium percentage and pollution index so is there any other parameter p whos most responsible factor to pollutent as a indicator

There is no most important factor to measure. It always depend on the river you want to test and origin, and history of water. It seems to me impossible to give more precise answer as already answered by sam. Additionally, sodium absorption ratio, sodium percentage are only  one of the multiple dimension you have to control about mineral equilibrium. Be careful to have only partial quality evaluation that could induce false conclusion about water quality suitability.,

In Australia, river water to be supplied or to be used for irrigation, agriculture, livestock, aquaculture are monitored to assess the quality. These include for example, salinity/EC, pesticides, herbicides, trace metals and sometimes microbial pathogens, dissolved oxygen. There’s is a national water quality guideline for freshwater and marine water quality (ANZECC and ARMCANZ 2000) which provide trigger values for a range of water quality parameters to assess the suitability of river water for agriculture (chapter 4 focused on water quality for irrigation) (see the below reference)

Reference

Australian and New Zealand Guidelines for Fresh and Marine Water Quality (2000).http://www.environment.gov.au/system/files/resources/53cda9ea-7ec2-49d4-af29-d1dde09e96ef/files/nwqms-guidelines-4-vol1.pdf