We know that every nutrient has a critical limit for rice. But I need to know about critical limit of exchangeable sodium percentage (ESP) for rice. I have found from a literature that its value is 10. Is it right?
Salt tolerance indices including the threshold ESP, slope which represents yield decline per unit increase in ESP and the value of ESP at which yield is reduced by 50% are reported for 20 crops. In respect to threshold ESP, Sesbania is the most tolerant of the crops tested followed by rice (transplanted) and wheat. These are the only three crops in which threshold ESP exceeds 15. effects of exchangeable sodium percentage (ESP) levels of 82, 72, 65 and 35 and 0, 15 and 30 days of presubmergence (submergence prior to the transplanting of rice) on yield and chemical composition of rice and availability of Fe, Mn, Zn and P in soil were studied factorially in a field experiment. Tolerance of crops to soil sodicity as represented by high exchangeable sodium has been examined utilizing data from field and greenhouse studies.he cumulative effect of ionic imbalance and water uptake are found to be the factors governing tolerance differences.
The sodicity tolerance indices reported herein represent the relative sodicity tolerance of crops to high exchangeable sodium and could be used in management and crop planning in amended sodic soils and/or management of sodic waters.
Article Response of crops to high exchangeable sodium percentage
Article Effect of exchangeable sodium percentage and presubmergence ...
Nice question . Critical ESP is texture and crop- dependent . For example , if an ESP of 15 is critical for illitic loamy soils of IGP , only 7-8 ESP is critical fro smectite soils, regardless of crops. Unfortunately , critical ESP with regard to crops is distinctively not so candid...
In the Sys et Al (1993) Land evaluation, part III: for rice ESP% is optimal in 20
This issue was studied thoroughly by I. Shainberg. I suggest to read his book (Shainber and Shalhevet 1984). The values were in the range of 10-12%. In his publications, He tried to convince that ESP is the best index to salinity, rather than SAR.י
According to Lamond, R. and D.A. Whitney ESP values of between 0-10% have no serious consequences on the soil but values above 10+ % favour soil dispersion as a result soil physical conditions are poor and impede plant growth.
Probably soil texture , besides soil mineralogy will dictate the critical soil ESP.
Whether ESP is more reliable parameter than SAR will depend upon the association of salinity with sodicity . What is EC of soil ...
Dr. Srivastava has a point. I have worked with vertisols that are high is smectitic clays. Some of my colleagues have noted that dispersion is these soils starts appearing when the ESP is in the 5-7% range. mineralogy (type of clay) is important.
Rice is moderately tolerant crop so that good crop growth obtained up to 15 ESP but the ESP range 20-40, the growth of rice stunted due to both nutritional factors and adverse soil condition. Whereas the growth and yield of sensitive crops like pules (Cicer arietinum, Cajanus cajan, Pea, LENTIL etc.) are affected at ESP levels below 15, only extremely tolerant native grasses grow at ESP above 65.
Critical ESP with respect to a given soil type and crop type will again be dependent upon whether or not , the said crop is rainfed or irrigated..?
I agree with Dr. Srivastava ESP veries to depend crops and soil types but ESP only criteria of sodicity measurment
Recent research indicates that ESP/SAR is no more a relevant criterion for sodic soils; it is seen than saturated hydraulic conductivity < 10mm/hr a much better criterion to relate the crop productivity. A relevant pdf is attached for kind perusal.
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