Dr. Rao very interesting question. The S added needs it oxidation to be converted into different plant avaialabe and non-available forms. Under aerobic conditions this takes about 3-4 months but under an-aerobic conditions this time is much longer. So I think the ecological conditions of the crops, among others, must be causing the differences in S use responses.

there are 2 main reasons for the low utilization coefficients of S fertilizer:

1. the high mobility of sulfate in soils make it prone to rapuid leachig. This can be overcome partly ba appying ellemental S which needs odidation prior to plant uptake, but also this oxidation goes quite rapid in soils with established Thiobacills.

2. from begin of evolution plants have developed active trransport mechanisms for sulfate to keep ionic homeostasis (keep in miind that in the beginning of evolution of plant life the atmosphere contained much higher sulfur loads!). This limits the S uptake closely to the requirement of the primary metabolism. Only in species with a significant secondary S metabolism (e.g. Brassica and Allium species) more S than the primary metabolism assimilates is taken up.

Among the plant Kingdom the onion and cabbage family stand out for their ability to accumulate Sulfur based compounds. As a diet source the Egg stands out. The Sulfur based compounds are essential in the defensive metabolism of these Sulfur rich plants. The use of these plants should be considered nutritionally also in relation to their ability to stimulate thyroid issue such as goiter. Nutrition is always a Goldilocks situation.

The ability of Sulfur accumulating plants to stimulate defensive reaction in the animals and humans consuming them is also well known. Garlic of course is known as Russian penicillium. Methionine is an essential amino acid not made by man and can only come from our diets.

When it comes to using cabbage family plants they are notable for not being mycorrhizal. The onion family plants have a heavy sulfur metabolism but is highly mycorrhizal dependent.

Concerns about Sulfur deficiency has been reduced since huge amounts have been spread related to the thermoelectrial industry based on coal which is a major source of atmospheric Sulfur. In the Eastern half of the United States the acidity of rainfall is 4.3 while the nonindustrial rain would be 5.6 or 150 more alkaline.

The ability to stimulate better plant and animal health can be fostered while increasing the use of high Sulfur using plants in the crop rotation. Oil radish can be effective for breaking up compact layers in soil as well as biofumigation against soil borne weeds and pathogens. Since these can be deep rooted they can harvest Sulfur from the deeper soil levels and recycle it into top soil for better use.

While most concerns in areas such as Eastern United States and Northern Europe is will the role of Sulfur in acidity issues, under a semi arid environment of alkaline and carbonate issues with high potential for Salinity, the use of sulfur from scrubbers would potentially be highly beneficial in about one third of the globe in arid and semi arid condition with excess alkalinity.

In terms of improved nutrient efficiency in Sulfur as in other nutrients I feel this is best accomplished by adjusting pH optimally removing soil physical constrains and optimizing biological recycling and using a focus on the soil Carbon dynamics which serve to retain and recycle the nutrients needed for our plants, animals and ourselves.

Rather than a narrow focus on efficiency of nutrient use in chemical sense we need to focus on the Carbon capital of our soil resources and then the conversion rates are still low but higher than the depleted soil and because our soil Capital is much higher the optimize recycling will lead to optimize crop animal and human results.

Some Sulfur thoughts for your day.

I thank Drs.Hepperly, Schnug and Ghafoor for their excellent inputs.Oxidation of elemental sulphur has two issues - one  the period of oxidation and the other one change in pH.Possibly the period of oxidation can be reduced by using native or inoculated Thiobacillus ,use of some new products like micronized sulphur and bebtonite sulphur.As mentioned by Dr.Hepperly, sulphur oxidation may help to reduce pH in alkaline soils and aid in their amelioration.But caution is needed when we use elemental sulphur in neutral and slightly acidic soils for possible pH reduction. Traditionally we paid attention to sulphur  nutrition in oilseed crops like Brassica,mustard.Of  course onion and garlic also received attention. Dr.Hepperly has provided interesting information on role of sulphur in defensive mechanism,link with goiter(Thyroid metabolism),antibiotic properties of garlic.Of course Indians also know the  medicinal value of garlic.The oil radish is new to me.Apart from elemental S,the sulphate -S is also being used as source of sulphur and the mineral and phosphogypsum are quite cheap sources of S compared to the elemental S.How to meet the sulphur requirement of crops in diverse soils and improve its use efficiency are important issues.I request Dr.Schnug to share his  interesting information on role of suphur in colour,shape and aroma of flowers .

You have to separate between the general question why fertilizer efficiency is low (independent on the S source!) and the specifics of elemental S , which is a complete different story. Browse our publication portfolio, you will find a lot of information to both issues as well to  the field of SIR, Silphur Induced Resistance, which is a lot more than just glucosinolates!

Dr.Schung ,thank you for the good suggestions.

We should meet one day and discuss the subjct live, dear Annangi! Its so very much exciting!

Let us see how opportunity comes up.Thank you.

While going through the responses, I got a doubt  whether the crops like mustard,onion,cabbage etc with high S requirement have  high sulphur use efficiency?.Whether the soil native gypsum,SO4-S in irrigation water and crop residue  and manure mineralization in soil etc contribute sufficient S to crop and lower the use efficiency of  Sulphur fertilizer?

Dear Dr. Rao in one of studies here in the Indus Plains of Pakistan indicated that in irrigated areas, S balance (= S added in water, fertilizers, mineral weathering etc - S removed by crops, leaching, in-situ immobilization/precipitation) was positive, i.e. S added was more. The study also concluded that for most of the field crops there is no need to apply S.

Dr Subba Rao

you already have vast experience of balanced fertilization for crops as well development of customized fertilizers/fortified inorganics, in which we are able to enhance the efficiency of all the nutrients part of the customized material, and enhance the growth and yield of crops.

regards

If mycorrhizae are not optimized it will greatly reduce Sulfur efficiency. Optimization of Sulfur is indeed a worthwhile issue since Sulfur plays such critical biological roles in plants and animals. I believe the use of onion family crops will help optimize Sulfur economies in the soil as they have high use and dependency and they are heavily mycorrhizal. 

As the clean energy movement takes hold one of the side effects is that the Sulfur requirement will not longer be supplemented from Coal burning from thermoelectrical power generation. In the Eastern United States and Northern Europe this is already occurring. The soil economy will change because of these changes.

If we are going to optimize our soil environment for Sulfur and other elements pH seems to be key issue and I worry that most soils around the world are not optimized for their crops and soil reactions. If we have either alkaline soils over 7.3 or acid soil under 5.7 there will likely be potential of multiple dieficiences and toxicities.

Thank you Drs Ghafoor,Kalra and Hepperly for your comments.Dr. Ghafoor,balance sheet approach is important both to avoid unnecessary depletion and also accumulation of nutrients in soil.Simple soil test  with chemical reagent may not guide properly to arrive at sulphur recommendation without the knowledge of mineralization/solubilization of sulphur from soil.Also the contribution of irrigation  water especially from ground water and  crop residues left in the field and composted manure applied.I agree with you Dr .Kalra that application of small amounts of sulphur through innovative products will definitely increase their use efficiency in S deficient soils Dr.Hepperly, as in case of N and P,in case of sulphur also we have to exploit/use efficiently the biological systems. Optimization of soil reaction is equally important but we have economic hurdles to go for liming acid soils but manure use is advocated .Sulphur availability is also a problem in countries like India.One balance sheet suggests currently a negative balance of 0.5 millions of S in Indian agriculture.

Dr Rao one reason for S balance being negative in India, I think, is that the soil water system is dominated by SO4 and Cl ions, almost in the ratio of 49 : 49, while 2 % remaining are the HCO3 and CO3 ions while borates are found in highly saline-sodic soils and waters. But in India, CO3 and HCO3 are more, owing to which usually pHs exceeds 8.5-9.0 in India but  here in Pakistan seldom exceeds 9.0. This perhaps could be due to differences the geological parent materials of soils of both the countries.

Dr.Ghafoor,good  information.There is no sufficient data base on irrigation water  contribution to sulphur balance in Indian agriculture.However several authors reported substantial contribution of irrigation(ground) water to sulphur nutrition  of crops especially from Punjab state .

The contribution of sulphate in soil water (and irrigation water)  is indeed one of the most significant contributors to a crops S balance and quantitative much more important than S released from OM mineralisation. Its also one reason which further reduces fertiliser S utilisation. Here you find some more infomation:

1.          Haneklaus S., Bloem E.,Schnug E. (2010) Sulfur nutrition. Encyclopedia of Soil Science, Taylor and Francis, DOI: 10.108/E-ESS-120045-499

2.          Hartmann, Knut (2019) Räumliche Modellierung der Schwefelversorgung von Kulturpflanzen für das Gebiet der Bundesrepublik Deutschland. Dissertation TU Braunschweig.

3.          Silvia Haneklaus, Elke Bloem and Ewald Schnug (2008) History of Sulfur Deficiency in Crops. In: Sulfur: A Missing Link between Soils, Crops, and Nutrition. Jez, J. (Ed.), Agronomy Monograph No. 50, 45-58.

4.          Engler, M.P.C., Cichota, R., de Jong van Lier, Q., Bloem, E.M., Sparovek, G. and Schnug, E. (2008) An alternative approach for the determination of soil water mobility. Pedosphere 18 (3): 328-334

5.          Haneklaus, S, Bloem, E., and Schnug, E. (2007) Sulfur Interactions in Crop Ecosystems. In: MJ Hawkesford and LJ DeKok (eds) Sulphur in plants – an ecological perspective. Springer, Dordrecht, 17 – 58

6.          Bloem, E., Cichota, R., de Jong van Lier, Q., Sparovek, G. and Schnug, E. 2005. The importance of low mobile soil water for the S supply of plants. Landbauforschung Völkenrode, Special Issue 286: 1-10.

7.          Haneklaus, S., Bloem, E., Schnug, E. 2003. The global sulfur cycle and its links to plant environment. In: Sulphur in Plants. Yash P. Abrol & Altaf Ahmad. (Eds.), Kluwer Academic Publishers, Netherlands 2003, pp. 1-28.

8.          Bloem, E., Haneklaus, S., Schnug, E. 2003. Model Based Prognosis of Sulphur Deficiency. In: Sulfur Transport and assimilation in plants – regulation, interaction and signaling. Davidian, J.C., Grill, D., De Kok, L.J., Stulen, I., Hawkesford, M.J., Schnug, E., Rennenberg, H. (eds.) Backhuys Publishers, Leiden, The Netherlands, 171-173.

9.          Bloem, E., Haneklaus, S., Schnug, E. 2002. Die Schwefel-Versorgung richtig einschätzen – So funktioniert das neue S-Vorhersagemodell “MOPS”- . dlz Agrarmagazin 4/2002: 56-60.

10.        Bloem, E.; Lilienthal, H.; Haneklaus, S.; Schnug, E.; Kleefisch, B.; Müller, U.; Schäfer, W.; Kues, J. 2001. :BUNDESMOPS – Ein Konzept zur Vorhersage von Schwefelmangel auf landwirtschaftlichen Flächen in Deutschland. NLFB Fachtagung „10 Jahre Boden-Dauerbeobachtung in Niedersachsen“ 17.-18.10.2001 in Hannover.

11.        Haneklaus, S.; Bloem, E.; Schnug, E. 2002. Sulfur. In: Encyclopedia of Soil Science (edited by Rattan Lal),  Marcel Dekker Inc., New York, ISBN 08247-0634-x, 1282-1288

12.        Bloem, E.; Haneklaus, S.; Schnug, E. 2000. Modell zur Vorhersage von Schwefelmangel auf landwirtschaftlichen Nutzflächen in Deutschland. DFG-Programmkonzeption Geotechnologien, Leitprojekt VIII “Stoffkreisläufe“, 30.08.2000, Hannover.

13.        Haneklaus, S.; Bloem,E. 2000. Sulphur in Agroecosystems. Fol. Univ. Stetin. 204 Agricultura 81: 17-23.

14.        Bloem, E., Haneklaus, S., Schnug, E. 2000. Bedeutung von Standort und Bewirtschaftung für die Schwefelversorgung. 110. VDLUFA-Kongreß 1998 in Gießen, VDLUFA-Schriftenreihe 53/2000, 7-18. ISBN 3-922712-79-7

15.        Bloem, E., Haneklaus, S., Schnug, E. 1998. Influence of the soil water regime on the S uptake of plants. Abstracts of the 1st Workshop of COST 829, Goslar.

16.        Bloem, E. 1998. Schwefel-Bilanz von Agrarökosystemen unter besonderer Berücksichtigung hydrologischer und bodenphysikalischer Standorteigenschaften. Dissertation TU Braunschweig. Landbauforschung Völkenrode Sonderheft 192.

17.        Schnug, E., Bloem, E., Haneklaus, S. 1995. Significance of soil water dynamics for the sulphur balance of oilseed rape. Proc. of the Ninth Internat. Rapeseed Congress „Rapeseed today and tomorrow“, Cambridge, U.K. Vol. 1 to 4, 287-289.

Thank you Dr .Schnug for the good information provided and a lot of references provided.The references will be useful to me,the followers and viewers of this question.In tube well or ground water irrigated areas ,the knowledge of sulphur status of water will help to refine the sulphur fertilizer recommendations.When manure is applied with S fertilizer ,the contribution from manure can also be deducted from the fertilizer recommendation.The incidental addition of sulphur from other fertilizers added to soil also need to be accounted for.

Thanks a lot for the nice information provided, which helps all of us to look deeply into this imp subject

When electric generation in United States was generated with coal without scrubbing there was little concern about Sulfur deficiency as abundant sulfur was provided from the coal emissions. When the Sulfur is scrubbed it also gives a disposal issues.  As other sources of electricity are being exploited the abundance of this input will diminish.

Another issue is the use of anhydrous ammonia rather that Ammonium sulfate in relation to setting a plate for Sulfur deficiencies. It seems that the ability to incorporate crucifers in the crop system can be use to improve Sulfur resources in the soil for subseqent crops and also have a curative soil fumigation effect. 

When single and purified nutrients are used more care needs to be used that nutrient disbalances are not the result.  Purified sources are more concentrated reducing in particular the transportation cost but cruder sources can have long term advantages related to the supply of micronutrients as examples. 

In all cases these issues point to the need of plant and soil analysis to accurately access the potential for toxicities and deficiencies and pertinent levels for each location of interest. 

Dr.Hepperly, I agree with your comments and suggestion. In India both mineral and byproduct sources and concentrated  sources are being promoted. We need to follow cropping system based sulphur management and take the aid of soil and plant testing to apply requisite amount of sulphur to crops.

----

Genetics. Little information is available on the genetic determinants of sulfur use efficiency. It would be great to see more work in this area. Genome-wide association methods are available for just this type of analysis.

Among the crops that are most Sulfur dependent are the cabbage or mustard family Brassicas. As Evald points to.  They produce pungent isothiocyanates which are sulfurous in content. These plants when incorporated into soil not only bolster the Sulfur availability but also work to biofumigate the soil from weeds, insects, pathogens and nematodes. The environmental and economic impacts of biofumigation would merit a much greater use of the technique along with solarization for non chemical pest control. A drawback of the this family is that they reduce beneficial mycorrhizal fungi because of not being hosts for them and the fumigant effect. These plants also respond greatly to Sulfur addition with higher yield and quality. Many are highly productive and healthful in diets and need to be utilized in diversified agricultural systems as rotational crops in mixed agricultural systems. Sulfur addition can be by cover crops and by mineral sulfur addition. Sulfur has an excellent use for pH modification and about 25% of global arable lands are not optimized based on excessive alkalinity.  Since Sulfur amino acids are the major essential amino acids for complete proteins in legume complemented diets this is another reason to champion the greater appreciation as well as Sulfur proteins appear to have defensive roles in plant metabolism generally. Among these plants oil seed radish is notable for ability to breakdown compacted soil plow pans and also serves as biofumigant and useful food known as Daikon in Japanese cookery. The enormous and deep tap root is a type of biological chisel plow. 

Some thoughts. PRH

Dear Dr.Hepperly,I whole-heartedly compliment your comments on the great role of sulphur in soil-plant-human system.I  agree with you that sulphur needs greater attention in future researches on the aspects you highlighted.I  wish that you will contiue to guide young generation with your enlightening comments ands messages.

Wish you and your family very happy new year

.I also wish very happy new year to all the viewers and participants of the discussion.

Dr.Thomas,good suggestion.I agree with you that more researches are needed on genomic studies for better utilization of applied sulphur by crop plants.

Dear Dr. Subba Rao and other RG friends,

Many researchers recorded S deficiency in oilseed crops despite sufficient amount of sulfate-S available in the soils. This could be attributed to the ineffective xylem-to-phloem transfer of SO42−, because of its higher accumulation in the vacuoles of the mature leaves compared with the middle or younger leaves. The results evidently suggested that the oilseed crops like rapeseed and mustard are inherently inefficient in S utilization within the plant.

Reference: 

M.M.A. Blake-Kalff, K.R. Harrison, M.J. Hawkesford, F.J. Zhao, S.P. McGrapth (1998) Distribution of sulfur within oilseed rape leaves in response to sulfur deficiency during vegetative growth. Plant Physiol. 118: 1337–1344.

Dr.Kundu,interesting information and reference.I shall go through the reference.

As you mentioned, the Biodiversity Indexing of various environments support various populations of plant associated microbial biomes. Sulphur requires biochemical manipulation, usually by microbes to be effectively used by many plants. There is a lot more to it, but there lies your basic answer. You have some very good resources. Dr. Jordan

The inefficiency of Sulfur is probably akin to the inefficiency of Nitrogen which is lost as the oxidized anion as leaching and as gaseous volatilization. For most plants, the requirement of Nitrogen is about 10 times of the Sulfur. Sulfur supplementation does not need to be overly expensive as 200 kg/ha gypsum would supply for Sulfur rich crops such as brassicas.  In terms fertilization ammonia application is problematic based on the acidification which leads to aging and losses of soil quality in many situation. The best sustaining and regeneration strategy is using biological nitrogen fixation and developing farming systems that optimize soil organic matter. In relation to Sulfur many arid and semi arid areas are alkaline and elemental sulfur can be very effective in reducing alkalinity issues. In relation to  providing for Sulfur without moving the pH values gypsum is the best option.  Soil situations are optimized by maintaining soil pH within an ideal range and this affects the availability of macro and micro elements. Even so many producers around the World in both developing and developed countries fail to address pH issues proactively through preventive and remediative programs. Finally many if not most issues of micro and macro element nutrition can be relieved when soil organic matter goals combine with the soil balancing and pH goals. 

Dr.Hepperly ,I fully agree with you that pH adjustment and regular use of organic manures, legumes in rotations and cover crops solve many nutritional problems of crops.Also use of gypsum or single super phosphate ( a source of P, Ca and S) which contains 50% gysum can be good sources of sulphur especially in oilseed and pulse crops.In India we  can reduce the amount of diammonium phosphate imported every year.We can use our  low quality rockphosphates(by beneficiation and by mixing with high quailty rockphosphates) for the manufacture of super phosphate.

How far should answers stray away from the original question, dear colleagues?????

Dr.Schnug,I agree with you to some extent if one sees the question in true sense.If  we see sulphur resources in soil- plant system and their efficient use ,then we are not deviating much.By adjusting soil pH and making available the sulphur present in soil one can increase the efficiency of S utiliation. Elemental sulphur sources like micronized S,Bentonite sulphur etc.are now being promoted for application in smaller amounts and their efficient use by crop plants.For countries like India which are importring sulphur,the use of alternate sources like mineral gypsum and byproduct gypsum is also important.Of  course we have to see the efficiency of utilization of these products or their  improved versions.Even enriching the single super phosphate with other S sources is also an option.

Sulfur efficiency might be low because the cropping system do have mycorrhizal associations optimized.

Sulfur is also important for the production of onions and garlic which belong to the family Amaryllidaceae, which is the source of pungency and flavor. Since most sources of sulfur fertilizers are acidifying soils, getting sulfur sources that do not exacerbate soil acidity is a bit difficult as soil acidity in the humid tropics is a critical problem.

Gahan, J., and A. Schmalenberg. 2014. The role of bacterial and mycorrhiza in plant sulfur supply. Front. Plant Sci. 5:723.

Most sulfur is found in organic forms and the role of bacteria and mycorrhizae are critical to the conversion into water soluble ions and the movement into the plant which is likely through mycorrhizae in amf plants. Onions are highly mycorrhizal and brassicas do not exhibit amf. The rhizosphere bacteria make be stimulated in a tripartite plant fungus and bacteria interactions.

Dear Getachew Agegnehu,, While elemental sulfur is an issue in red soil acid soils. The use of calcium sulfate does not lower pH and can be used to provide sulfur economically. In the acid tropics the use of lime and ensuring both Calcium and Sulfur are sufficient would foster greater efficiency and productivity. When sulfur is lower the lower pungency as in onions led to premium sweet onions in Vidalia in the state of Georgia which has low sulfur availability. In addition sweet onions have a low genetic ability to produce the pungent constituents based on sulfur. Although sulfur in diets can be an issue with bad breath and body odor the constituents are notable for their anti and probiotic capacity.

The reasons behind low sulphur use efficiency may be that sulphur is adsorbed by some minerals and other losses(leaching and erosion) is there in soil. And some amount of sulphur is immobilized ...................