URGENT PRACTICAL QUESTION
- Timing of nitrogen fertilizer application is key in nutrient management in agriculture.
- Nitrogen is considered the most mobile plant nutrient in the soil, hence timely application is necessary. Phosphatic fertilizer applied during the sowing of seeds is sufficient enough to sustain the seed until spring.
- N application should best be applied in spring when plant root establishment in the Rhizosphere is at maximum (Shicheyi Philip, 2021).
- N becomes the most limiting factor even in developed countries, leave alone the smallholder farmers, because of untimely application, with over 70% approximated as wastage due to leakage (Shicheyi, 2021).
- Until and unless plants have roots they cannot utilize the applied fertilizers (Keshab, 2021). Potassium and phosphatic fertilizers take a little longer time to be ready for the plants. Therefore they must be applied as basal.
- There should be the wise application of Nitrogenous fertilizers as they are lost through volatilization, leaching, and runoff water. If Phosphatic fertilizer is a complex one with some amount of N, it is not necessary to apply additional N through Urea or other sources (Keshab, 2021). This is the reason, instead of applying 50% N as basal; increase the number of top-dresses at various stages. It will automatically increase the N use efficiency by crop.
- It must be noted that basal use of N is recommended if and only if it is combined with a urease inhibitor (Shicheyi, 2021).
- Nitrogen is most needed during a plant's vigorous growth stage which obviously is not basal (Shicheyi, 2021).
- Moreover, unused Nitrogen in the soil can lead to ammonification which in itself is a source of pollution and CFC.
- Normally, agriculturists recommend 50, 100, and 100 kg/ha of N, P205and K20, respectively as a basal dose (Keshab, 2021).
The bottom line concept is, 'Supply plant nutrient at the right time in the right quantity and quality."
So:
- when is that right time?
- is the basal application of N fertilizer scientifically correct?
Dear RG professionals, could we get references for your valuable answers?
STAY BLESSED!!!
Alem
Alem Redda I will answer your questions sequentially,
1. Is basal application of N correct?
My answer is YES and NO. In technical terms, basal application of N means application of N fertilizer(s) before or during sowing of seeds or planting of seedlings. Thing one, N is highly volatile. Thing two, volatility of N is directly dependent on soil types and agri-climatic conditions such as temperature and rainfall amount. Thing three, all other factors being ideal, N volatility of basal application in seeds is higher(hence not recommended) than seedlings with established roots(hence can be recommended).
2. For how long does N stay in the soil?
From my answer in (1) above, it is clear that there is no specific universal agreed time it takes for N to stay in the soil. Different soil types have different nutrient holding capacities exiting in different agro-climatic zones. For example, N will take the least time to stay in sandy soils with higher temperature/rainfall intensity as it would take in clay soils with low temperature/rainfall.
Dear Dr. Shicheyi Philip,
really many thanks to you. You always add spice to the subject.
- The volatility of N is dependent on soil types and climatic conditions.
- Basal application is not recommended for direct seed sowing
N.B. In case we got references, let's not forget to share them among us.
STAY BLESSED!!!
Alem
It depends. Which crop will be grown in the area? What is the content of Organic Matter?
Dear Dr. Huan Pablo de Souza, thank you for your valuable suggestion.
I'm doing on rain-fed maize.
What the organic matter has to do for the applied N fertilizer, if we said the sown dry seed can't absorb the already applied N during sowing?
Sir., do you have any references?
STAY BLESSED!!!
Alem
Dear Dr. Huan Pablo de Souza , thank you for your valuable suggestion.
I'm doing on rain-fed maize.
What the organic matter has to do for the applied N fertilizer, if we said the sown dry seed can't absorb the already applied N during sowing?
Sir., do you have any references?
STAY BLESSED!!!
Alem
Dear Mr. Alem Redda, hope you're well
A way to know the right time is looking for nutrient absorption models of rain-fed maize, as presented in the works bellow:
Article Maize dry matter production and macronutrient extraction mod...
Article Responses of dry matter, nutrient uptake and grain yield of ...
Dear Dr Gabriela Carvalho Maia de Queiroz ,
thank you for your valuable sources.
Luckily, I'm doing on rain-fed maize. For maize, it takes 6-9 days to emerge (after dry sowing). So, what is the merit of applying urea at dry seed planting? How the maize could use N without having roots and enough body to utilize that N?
N.B.
- N uptake (the maize didn't have roots at these sowing to emergence days)
- N utilization (the maize plant didn't have enoughbody to utilize)
Dear, please tell me about your practical experience on N application @ sowing!!!
Thank you for understanding my concern!!!
STAY BLESSED!!!
Alem
Lots of papers can be referred for this idea; I advice you read the article: https://downloads.hindawi.com/journals/ija/2017/1545280.pdf
Thank you!
Dear Alem,
The interesting discussion you raised. But I wonder the question you raised to Dr Gabriella. If you are dealing with the rainfed system why does it stay dry for that length of days? I tell you if it is dry for these specified days then the probability of germination is very low ( if you apply N at planting). This is because the applied nitrogen will be changed to gas that kills the living seeds. We have had great experiences with this. I remembered a similar question was raised by the Ethiopian Ministry of Agriculture some time beore. Forget the dry planting and argue to what extent the seedling will be supported at least with nutrients existing in the edosperm? 2 leaves stage, 4 leaves stage etc.? I advise you applying N at planting has a lot of advantages but it must be the lowest fraction from the total dose.
Dear Dr. Tadele Amare Kassie, really thank you for your enthusiastic efforts and insightful concepts. You've even added good spice to my question (2, 4, etc. leave stages!!!)
Regarding my concern, I'm not saying dry spell after sowing. I used the term "dry seed" b/se someone here commented that if we said only "planting" it could also mean for e.g. planting of seedlings, cuttings, bulbs, etc.
What I'm saying is let we have ample moisture (i.e. the rainy season has started). For example, maize takes 6-8 days for germination. If we apply N fertilizer at sowing (dry seed; not seedling or else), how could the plant use it? One thing, the plant is immature. 2nd, the plant itself hasn't mature enough roots to uptake the N.
You've mentioned the three helpful and critical ideas:
- the endosperm of the seed has reserved food.
- If no moisture, the applied N will kill the living seeds
- N at planting has a lot of advantages
Now, my big questions to you and all RG scholars are:
- for how long could N stay in the soil until it would be absorbed by the roots (Synchronization)?
- what is the advantage of N @sowing if the plant has no meaningful roots and leaves?
Dear Dr. Tade, you've said that "applying N at planting has a lot of advantages". Does N have other benefits other than being food for the plant?
Wish you all the best this life can deliver!!!
Alem
Basal application of N fertilizer is correct but not all the recommended dosage as basal, apply N fertilizer in split doses during different crop growing period like basal during sowing and transplanting, tillering etc.
Dear Dr, Chandrakala M., thank you for your response. But what you said seems a general idea. Split application is, of course, clearly nice. Say, e.g. 100 kg/ha urea is required for maize and we are to split it into four. 25kg/ha as basal application. But the question is that N is such a very volatile and mobile nutrient; plus the maize plant at this stage has no effective roots to absorb it and no effective body to utilize the N nutrient.
- So, what is the value of adding N at sowing?
- N.B. We are talking about seed planting; not seedling, cuttings, bulbs, etc.
Please, share any article regarding this critical issue.
Thank you for your understanding of my concern.
HAPPY NEW YEAR!!!
Alem
The need of crops like maize or small grains follow their growth cycle and biomass.
In maize or these grains most nitrogen is need from 10 to 20 cm height to the reproductive stage. flowering stage.
A split application would most like optimize the use of nitrogen which does not last over 3 weeks in the soil.
The nitrogen could be applied at preplanting but double the rate would be needed for optimized usage.
In maize if at the knee stage there is over 20 ppm Nitrate in a soil test the need for extra nitrogen would not be justified.
Using the nitrate side dress option the nitrogen can targeted only to the responsive environment.
If in the case of rotation with legumes manures and cover crops the soil condition can improved to an extent that over time the plants like grains can be grown on the soil resource without need for high rates of nitrogen application.
While fertilzer would be sorely needed in soil of 1% or less soil organic matter a soil of 5% or more soil organic would nat necessarily respond to added nitrogen.
Iowa State Nitrogen side dress test can be used for conventional farmers to reduce their nitrogen application applying only as needed.
Dear Prof. Paul Reed Hepperly, thank you so much for sharing your insightful concepts!!! Amazing information and very well explained.
Farmers' practical questions have always been a mystery to me and now I feel excited to begin helping them.
But to make it perfectly matched to my critical study, how can I cite you for your good idea of "nitrogen does not last over 3 weeks in the soil"? Now, my new doubt is (if I am not mistaken), how N could stay for such a long time in the soil? That means I have to read a lot.
Or, dear Prof. could you please share a reference for me?
Dear Prof. Paul and all RG professionals, you are tremendously helping me to do better at work. STAY BLESSED for that.
Thank you.
Liebig the originator of the fertilizer model talked about addressing the most limiting factors as barrel stave analogy.
The water in the barrel can only arise to the shortest barrel stave.
That stave could be nitrogen but it slso be other nutrients in the field water is usually the most limiting factor.
The single nitrogen focus has much limitation.
If we focus on the soil organic matter we are addressing issues with nitrogen and with water.
Nitrogen in soil becomes available in response to increase cycling of soil organic matter.
The nitrogen from soil that can become available can be stimulated by increasing the nitrogen in soil and by increasing the rate of biological cycling.
The naive virgin soil organic rates were over 5% and nitrogen under than condition is not a big issue.
Our cultivated agriculture has dropped soil organic matter to generally less than 2% this low soil organic matter compromises soil nitrogen release and the aeration and water ability of the soil.
Rather than address the nitrogen solely we need to take more integrated approaches to soil fertility and the pH nutrient toxicities and soil organic matter need to addressed comprehensively.
I like to find the areas of problem diagnosis them and bring the field into improved uniformity.
This is a long term strategy as fertilize give immediate responses and soil improvement is a more sustained and deliberate posture.
Dear Dr Alem Redda . See the following useful RG link: Article Nitrogen Fertilization Increases Root Growth and Coordinates...
Kindly see the following very good RG link: Article Effects of Nitrogen Rates and Time of Application on Yield o...
Also check please the following useful RG link: Article Soil Nitrogen Distribution and Plant Nitrogen Utilization in...
Dears Prof. Paul Reed Hepperly and Prof. Aref Wazwaz, thank you for helping me to be able to help and serve farmers in the field with confidence.
Thank you for providing so many helpful tips:
- Prof. Paul for the clear and insightful explanations
- Prof. Arif for such so valuable references.
I wish I have so much knowledge as you do Sir. It is so amazing how you share your expertise in excel!!!!!!
STAY BLESSED!!!
Alem
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