Zinabu, one of the reasons for not applying the fertilizer in the same season when you apply lime , could be attributed to time given lime to react in soil to leave its reclamative effect , before full response potential of fertilizers could be experienced in field. Very often , it is seen , liming alone could bring such distinct improvements in soil fertility status of the treated soil .
It takes time for the liming material to react. The reaction is also a function of fineness of the lime grind and the mixing and wetting of the material.
Ideally in a winter wheat area the lime would be broadcast after harvest but before the planting season. The lime would be incorporated by deep plowing and then tandem disking. Ideally the liming is done in late July and August and the planting is done in the fall with advent of seasonal rains.
A first target for eliminating Aluminum toxicity would be pH 5.3 for eliminating Manganese toxicity pH 5.7 and for maximizing Phosphorus solubility pH 6.3. Overliming can lead to Manganese, Iron, Boron and Zinc deficiencies.
I agree with the account given by Dr.Hepperly on liming. Liming beyond pH 6.5 may not be desired. Many crops may come up well in soils limed upto pH 6.0.Fertilizers can wait for the next crop season.Because of increase in pH many nutrients become available to crop plants.Probably some nitrogen supplementation is needed.Other nutrients can be skipped in the season/year of liming.
Dear Zinabu,
Soil pH is a characteristic that describes the relative acidity or alkalinity of the soil . Soil pH is an important factor in determining crop performance Low pH levels affect nutrients by converting them into forms that are not readily available to the crop. In addition, low pH levels can increase the solubility of plant toxic metals such as aluminum resulting in stunted growth and a general lack of plant vigor. Many crops may come up well in soils limed upto pH 6.0.Fertilizers can wait for the next crop season. Because of increase in pH many nutrients become available to crop plants.Probably some nitrogen supplementation is needed. Other nutrients can be skipped in the season/year of liming. Nitrogen (N), Potassium (K), and Sulfer (S) are major plant nutrients that appear to be less affected directly by soil pH than many others, but still are to some extent. Phosphorus (P), however, is directly affected. At alkaline pH values, greater than pH 7.5 for example, phosphate ions tend to react quickly with calcium (Ca) and magnesium (Mg) to form less soluble compounds .
lime application does not always result in increased wheat grain yield and the cost of liming can sometimes be a limiting factor in the budget of a wheat farm. Changing soil pH is not always a rapid process. It sometimes take a year or more to fully realize the effects of agricultural lime, so the economics of broadcast lime on rented ground can be greatly influenced by the lease duration. Banding of phosphorus (P) fertilizer in-furrow at planting is an alternative strategy often implemented by farmers to reduce the negative effects of low soil pH. In-furrow P fertilizer can result in increased wheat growth and forage production in low pH soils by reducing aluminium toxicity and increasing the amount of readily available P to the crop.
Zinabu, one of the reasons for not applying the fertilizer in the same season when you apply lime , could be attributed to time given lime to react in soil to leave its reclamative effect , before full response potential of fertilizers could be experienced in field. Very often , it is seen , liming alone could bring such distinct improvements in soil fertility status of the treated soil .
In general liming is advised to apply at least before 30 days of sowing and fertilizer at the time before sowing and 50% of your N application you can split over at critical growth stages.
How do you see the size of lime particles to trigger of reclamative processes , besides the soil depth to which lime is to be mixed..? Whether crops to be grown will affect the depth to which lime is to be mixed..?
A pH of 5.5 is a threshold for most agricultural soils and crop types. Soils with higher buffering capacity are not sensitive for pH changes even with lower pH values than soils with higher pH values but with lower buffering capacity. Crops vary in their ability to grow in acid soils. For instance, legumes perform better in higher pH (6.5 or more) than cereals. On the other hand, horticultural crops like potato and tea grow well in acidic soils, even below pH values of 5.5.
Limes can be incorporated some weeks before planting normally after the main land preparation is done depending on the type of the liming material, that is whether slow or quick acting type. If it is a ground lime stone or dolomite it can be applied earlier than the quick lime as they are quick acting types. The good thing is that whenever the slow acting types are applied their residual effect may last from 3 to 5 years, based on the rate applied. So the exchangeable acidity, the soil pH and the rate of lime per hectare are determined liming materials can be applied some time before planting based on their type as mentioned above.
The time of lime application is by and large governed by the moisture availability in the soil . this can be facilitated either through irrigation , or by adjusting teh application with time of pre-rain showers ( Since everywhere monsoon rains may not occur) , and then later adjusting the time of sowing . I agree with you Getachew , selection of crop has strong bearing on their performance in acid soil . This is how , we optimise our ability to towards crop response. Again , residual effect is largely dependent upon the rainfall , physiography , annual versus perennial crops etc etc...We also need to give sufficient time for applied lime to be to react and leave some anticipated effect on soil environment . How much minimum time is to be given for applied lime to be really effective in terms of reclamative effect on soil environment ..?
Dear Dr. Zinabu, Dr. Tarafdar has rightly said that lime should be applied about 4 wk before sowing or planting of crop. Good mixing of lime with soil particles and allowing sufficient time for reaction are vital for desirable results. Again, moisture level of the soil and air temperature have strong influence on lime reaction with soil. In humid tropical condition, 4 wks time is good enough for achieving desirable effect of lime. Thereafter, in the same season, one may take up sowing/planting of crops with recommended application of fertilizers. Part of the recommended N as basal and full recommended doses of P and K may be applied at sowing/planting time, and the remaining parts of N may be top-dressed in splits.
Dear Zinabu,
Would you please consult research publications on acidic soils, particularly Nitisols in Ethiopia? I know a number of field trials have been conducted on liming of acid soils in Holetta, Chencha, Nedjo, Indibir, etc using the main crops in these areas, such as barley, faba bean, potato and maize. I hope you may find good information from the Ethiopian Journal of Natural Resources, Ethiopian Journal of Agricultural Sciences, and conference proceedings (e.g. Barley and Food and Forage Legumes proceedings published by ICARDA and EIAR).
However, as I tried to comment on your question above, the current practice is to apply lime and incorporate in the above 0-10 cm soil layer two to four weeks before planting.
Long term application of lime to acidic soils has beneficial effect if pH of soil < 5.5. The liming is to be done based on type of crop grown. Most of the horticultural crops perform better at pH 5.5. Of course, lime is to be applied at least one month prior to fertilizer application and should be mixed uniformly in the soil. Finer the particle size of the lime will have better response to soil.
Dear Sushanta Kumar Naik, I agree with your insight and assessment of a lime need when soil pH is less than 5.5 and that this need should consider carefully the fineness of grind.
Since Manganese toxicity is not problematic some people recommendation a target of 5.7 soil pH to lower lime cost and avoid overliming and potential for inherent micronutrient issues from alkaline inavailability. It is not a good idea to try to get to neutral pH and to do that rapidly.
In liming the Magnesium needs to be considered because many oxisols and ultisols can have very low Magnesium. I would suggest Dolomitic Lime in cases where the Magnesium level is the soil test is under 100.
In terms of overliming the use of 1 ton per hectare and then monitor year by year will avoid the overliming potential. While liming takes time for reaction this is also a function of humidity and temperature.
Monitoring can be a good route for gauging how practices are progressing. The deep inversion plowing with broadcast application and tandem disk incorporation is sufficient for giving good lime distribution.
Thanks for your thoughts in these important issues.
I do agree with you Paul , dolomite could be a better option , if magnesium is to be considered. Availability of soil moisture is a much bigger issue while deciding the time of lime/dolomite application .
Look at the subsoil pH: you may need to have deep amendment to allow plant roots to access subsoil water
Paul Milham,
Very good point of doing profile analysis which should include checking for compacted layers.
When a trench is made the profile characteristics can be quite telling.
Penetrometer readings can detail plow pans and pH measurement at different depths can show issues.
Moreover using the spade to look at root patterns can be telling also.
Do you have an estimate of the percentage of soils in Australia tillable lands which have pH issues?
I find your comments always very insightful. Paul Reed Hepperly
The liming in acidic soils with less than pH 5.5 is to be done based on nature of crop. It is true most of the horticultural crops perform better at pH 5.5. Good reply by Dr Naik and Dr. Anoop lime is to be applied at least one month prior to fertilizer application and should be mixed uniformly in the soil. Finer the particle size of the lime will have better response to soil.
This is really a good point raised by Paul (Milham) and later ratified by another Paul( Hepperly) , so Paul duo are doing excellent job to dig out some issues of real concern for all of us, kudos friends.
In most of the acid soils regions , sub-soil acidity is perhaps much bigger issue than surface soil acidity . And , Dr Malhotra is dead right in flagging off the point that deep rooted crops could be seriously affected by the consequences of subsoil acidity , when we consider the reclamation of acid soil considering the surface /plough layer depth only.
When soil is sandy and also when there is insufficient Calcium the ability to increase soil organic matter is compromised.
When fine fractions of either clay or silt are added and stabilized with Calcium the ability to elevate the equilibrium soil organic matter levels is elevated.
The subsoil which is often rich in eluviated clay can be a local source of material for sandy soils along with the abundant local lime access and residues and manures.
The combination of soil fines silt and clay with abundant Calcium and organic maters lead to complex which has more recalcitrance in the soil.
Our biggest obstacle to improving soil is lack of recalcitrance of the soil organic matter.
The bioengineering of the compost process is a soil lution to that issue.
This allows soil organic matter to accrue rather than be lost. The importance of this is water and nutrient are the biggest obstacles to cropping potential and soil organic matter is our biggest resources in overcoming these twin towers.
What you think?.
Nice response Paul , this is the ideal scenario , we are looking at while dealing with reclamation and effective management of acid soils. but , unfortunately most of the soil sites do not meet such requirement . addition of crop residues/organic manures could develop a kind of clay-humus -calcium complex , highly resistant against leaching losses coupled with stabilised carbon , will collectively do a world of good to the betterment of acid soils. Once gain nice response Paul..my compliments
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