Potassium is the third most important plant nutrient required in substantial amounts in crop production.Potassium requirement, quantitatively, is equal to or higher than nitrogen in many crops.Cereal straws,organic manures ,composts,wood ashes,industrial byproduct organic wastes contain substantial amounts of K.So,can organic recycling with the above mentioned or other organic sources meet substantial K requirement of crops and increase the crop production?
Plant contains up to 2% potassium. But organic matter can not contribute significantly in meeting the potassium requirement of crops.
Hello Subba,
I suspect you are asking a "Doroth Dix" since you have stated a generic K content of plants.
The K in plant debris is readily released (try boiling some in water) and there should be literature about K release during the decomposition of plant debris in the field and under controlled conditions.
So the answer is yes. However, crops use a lot of K, therefore to entirely satisfy their requirement would require a commensurately large amount of the organic material.
Regards, Paul.
Dr.Paul,I intentionally made the question broad based to give scope to several participants across the globe , to know diverse crops/cropping systems, and availability of a range materials and to what extent they can be recycled with out putting them to alternative uses.There are some K rich plant materials and by products which are being used/marketed .I request the participants to suggest all possible materials for a wide range of situations for efficient recycling.
not in a crop system which relies on internal cycling of its nutrients and this is mainly because K is most vulnerable to leaching. However, if a system accepts input from outside any kind of plant ash may be a significant contribution to beef up the P balance of a cropping system.
Dr.Schnug and Dr.Pal,internal K cycling is possible and good amount of K can be returned to/retained in the field in crops like banana which removes more than 1000 kg /ha field.The pseudo stem is retained on the field while the banana bunches are removed from the field.Similarly, the stem portions of papaya and pineapple can retained on the farm and the fruits can be harvested,thus considerable portion of >400 kg K taken up by crop can be retained in the field.In cereal crops >60% of K will in straw portion of crop.If crop residue is retained on the farm as in conservation agriculture very considerable amount of K can be internally cycled.Considerable amount of K in vegetable crop waste can be recycled from vegetable markets.Please suggest other possibilities for recycling organic wastes for meeting K requirements of crops.
Dear Dr. Rao the K in plants is readily available since it is not the structural component of any metabolites in plants, Very correctly said that washing plants in simple water can extract lot of K. Hence recycling organic matter could substitute plant K requirements. But this aspect is plant specific, e.g rice, potato and sugarcane based OM can contribute more to the system than wheat straw.
As pointed out by Dr.Ghafoor and Dr.Beri,rice straw,potato haulms and sugarcane(trash,sugar industry byproducts ) etc are good sources of potassium.Can some scientists provide information on food and agro-industrial wastes as sources of K.
I can quote one example on the potentiality of rice and wheat straw in supplying enough K.
Pal, D.K., Gupta, R.K., Durge, S.L., Sharma, R.P. & Khadka, Y.G. 2005. Role of fine-grained micas in potassium management of a long-term experiment on rice-rice-wheat system in soils of the Indo-Gangetic Plains at Bhairahawa, Nepal. Clay Research 24:63-81.
Dear Dr. Rao all the wastes from food industry could be a good source of K unless there some problem of cross contamination as there is no separate of collection the wastes from different types of industries.
The waste from sugar industry (Press mud, molasses) has been successfully used in crop husbandry here in Pakistan rather some sugar mills are now selling these to farmers. The wastes from fruit beverages (particularly citrus industry) are also used as organic manures by local farmers in calcareous alkaline soils.
Some time later I will refer you the exact sources of this information.
Thank you,Dr.Pal and Dr.Ghafoor for your inputs.In India also the sugar industry wastes are being used to supplement plant nutrients in agriculture..Press mud is composted and used.Dr.Ghafoor you are correct,both fruit and vegetable waste if collected separately ,they can be composted and used in peri-urban agriculture.
Dr. Rao, it was a good question and replied equally well by our learned scientists. The only thing to be remembered is that K will be released slowly by decomposition of OM. So there must be some initial K fertilizer in the start.
Dr.Hussain,Thank you for your comment.Actually potassium is not bound to any plant constituent but present as free ion in cell sap in large amount and so it is called ''master cation'.It is soluble in dilute acid and hot water .So potassium availability may not be a problem but released potassium can go on to soil exchange phase and so part of it may be held in exchangeable form and part in in solution phase.We normally take 60-70 percent of the exchangeable potassium in soil plant -available in soil test interpretation.So we can add some fertilizer K in the start along with organic material.
Dr. Rao, you are quite right. Addition of a starter dose will ensure no growth loss and subsequent effect on yields..
Not directly but by the interaction between the soil solution and the exchange complex.
As K is not bound in any organic compound its prone to quick losses from a system, e.g. by leaching. There is no single answer to the question of Dr. Rao, it depends on the individual situation: snalysing and calculating balances is more safe than guessing, dear colleagues!
Dr.Schung,as for my understanding, potassium losses by leaching can occur in sandy soils,acid sandy soils and soils with very high K saturation on exchange complex.In other soils greater amount of K will be in exchangeable form and thus protected from leaching.
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