Dear Doctor Rao

If you are able to develop a system of double cropping to enhance your maize and rice production and optimize Phosphorus. I would suggest that the cool season be used for a winter legume crop such as broad bean. This will provide an early crop and provide for main summer monsoon cereal maize or rice for example. I would encourage the application of composted manure to grain legume or winter cover and for summer grain crop the application of starter fertilizer with high Phosphorus, As the system would be employed the Phosphorus level would build based on composted manure residual and because more conclusive cover is maintained in the multiple cropping the mycorrhizal activity would increase allowing for better recovery. Particularly important for this success in the implementation of no till methods to conclusively eliminate erosion.

Thank Dr.Hepperly for initiating discussion on the subject I put up for discussion.Equipping the soil with good fertility before going for cultivation of main  cereal  crops with heavy nutrient removal is one good suggestion.In India it is often suggested to include a legume in rice-wheat,maize-wheat and rice-rice rotations.Where ever temperature and moisture regimes allow,one  can go for cover crops.Efforts are also going on to gradually go for conservation agriculture in important irrigated crop rotations.

100% water soluble fertilisers NPK 19:19:19 or. Monopotassium Phosphate etc can be used as spray at P.I. stage and reducing the doses of basal phosphate by 75% (trial needed) in order to have better utility of phosphate at reproductive stage. 

Dr.Das,foliar application is one opportunity to meet the P requirement of the cereal crop like rice and maize.One limitation of foliar application of nutrients is amount that can finally be  taken up by plants.So,reducing the basal dose is one concern and supplying sufficient amount at panicle initiation/heading stage is another issue.I request the participants of discussion to give their opinion on top dressing /split application phosphate fertilizers in reproductive stage, at panicle initiation or heading stage.

We know that the mobility of phosphate is very slow in soil, if top dressing of phosphate is advocated phosphate uptake at specific stage might not be proper besides the time for uptake would be less as against basal. Also at these stages there would be no extra root growth to reach phosphste applied in soil. So foliar application would be better to reach the target. Some micronutrients like Zn has synergistic effect with phosphorus in plant body, hence if applied in soil/spray might increase the effectivity of phosphate in plant body at these stages.

The over application of Phosphorus can be very inhibitory to plants by creating artificial Zinc deficiency.

The Zinc application is necessitated in that condition because the Phosphorus abundance signals plants there is no need for mycorrhizae and you have to very careful because Phosphorus utilization of plants in the natural soil is mostly through mycorrhizae.

Miracle grow soluble fertilizer is very high in soluble phosphorus and is also complete with  micronutrients a targeted spray at flowering may be able to get the kick the plant needs for the reproductive stage.

Most of the importance for Phosphorus has been traditionally attributed to early aggressive rooting which allows better ability to access soil resource.

I would suggest talking to Scott's in Ohio if they would suggest a targeted spray on maize and rice to see if this has any real impact under your situation.

Dr.s Das and Hepperly,like P the Zn requirement is also high in reproductive stage of cereal crops.So foliar application of both P and Zn may benefit the crops synergistic-ally.In the recent past ,with interactions with some agricultural extension professionals,I came to know that farmers especially in rice growing areas are going for split application of NP or NPK complex fertilizers,similar to earlier urea split applications at some important  growth stages.Also now farmers are aiming at very high yields.Probably in waterlogged conditions roots are able to access top dressed P.As has been repeatedly pointed out by Dr. Hepperly the addition of organic manures and participation of P solubilizing organisms including mycorrhizae my extend the period of P availability from the added P fertilizers by P solubilization and by reducing the P adsorption and fixation reactions.

In our state some rice growers use less phosphate as basal and due to ignorance they use NPK fertiliser as top dressing. The initial phosphate dose remains inadequate hence root growth hampered and further top dressing with NPK didn't help much to them. Under submergence there may be various types of interaction with Phosphorus which may or may not benefit depending upon other soil nutrient transformation

We need experimental data on the benefits of top dressing of P. Till such time, managing soil pH, additions of organics and P- solublizing cultures may help P availability through the reproductive phase.

Top dressed P is not be easily taken up by plants, because roots will be deeper , while top dressed P will be fixed in surface soil. If the tissue analysis of plants indicates P deficiency , foliar application of P is the only choice. Also one  is not advised to over fertilize with P, because most P in grains is stored as phytates, which are not digestible by humans and non-ruminant animals and are excreted leading to P pollution of waters. This is a major issue with the use of sewage sludge  and solid easte. Also phytates interfere with the Zn absorption by humans and may lead to  Zn deficiency. There are very few experiments with  foliar application of P and IISR should initiate such experiments on different soils in different parts of the country.

Dear Dr.Rajendra Prasad,I am very glad to interact with you on this important topic.I understand the international concern of excess P in seed in phytate form and its relationship with availability and absorption  of essential micronutrient Zn.Now efforts are being made to breed crop varieties with low phytate content.I also agree that foliar application and the other practices listed by Dr.Prakasarao will benefit the cereal crops.But the problem remains.Instead of restricting to  basal dose of phosphate (potash also) fertilizer application in the form of DAP/complex fertilizer, some farmers have started applying complex fertilizers in 2-3 splits like the earlier practice of urea top dressing.We have to ascertain whether any benefit is accrued to them with this practice What is the extent availability of the  top-dressed P to crop plants?.What is the consequence of excess accumulation of unutilized P in surface soil?I was told that this (split application of complex fertilizers) is practiced on soils adequate or high in available P also.One reason given is high P requirement at high yield levels as farmers are able to harvest almost 8-  10 ton/ha yields.

I agree with Dr. Rajendra Prasad; we need more experimental evidence on the top dressing of P and foliar application of P.

Dear Folks Reviewing the rice data from Arkansas Phosphorus and Potash Institute they observe a depression of yield as the Mehlich 3 soil phoshporus is over 25 and the soil pH is over 6.5. This is likely caused by Zinc Phosphorus antagonism I referred to earlier.

Zinc deficiency is considered a major problem in India and Southeast Asia which could affect 30% of the population based on prevalent stunting food choices and availability for Wessel and Brown 2012. This projected deficiency in about double the global risk of 17.3% according to their analysis.

A major cause of this risk is way food is processed with most Zinc being discarded with the polishing of rice.

My recommendation for optimizing your rice crop is to first look to 25 reading on your soil P1 second adjust pH in alkaline soil areas and I believe the use of zinc micronutrient seed treatment would be most cost effective in that case. 

A heightened awareness of the value of whole grains is perhaps a very valuable issues of nutritional significance in Asia and the World. 

Dear Dr.Hepperly ,it nice to interact with you again on some important issues.In India we are taking good care of zinc deficiency in cereal crops and other crops. In many Indian states like Punjab, Haryana, Uttar Pradesh and Andhra pradeh the number of zinc deficit samples have come down drastically.Agronomic fortification of seeds in wheat  is successful but in rice because of processing, zinc is lost in bran.Probably some where I have come across bran enriched or bran based biscuits.This can be one solution.In neutral and slightly alkaline soils adequate manure application may help in better utilization of residual P in soil.Innovative application of Zinc without much accumulation in soil will definitely help soil health and efficient use of resource.I  fully agree with your last sentence.

In relation the Zinc issue and the need to maintain a minimum application for maximum effect I would suggest testing the following. Seed treatment on the rice. Secondly two application of zinc at 15 cm top growth and at boot stage. I would suggest 5 kg urea and 1 kg elemental Zinc as Zinc sulfate and dissolving the spray with at least 100 liters of water per hectare. Data be taken on brown and white rice from the treatment. I believe this combination would raise foliar values to about 50 ppm and I guessing that critical levels for zinc in both brown and white rice would rise significantly. This would have significant effect on National health I believe when implemented at the farmer gate. Suggest the trial test have 6 small plot replications in 2 by 4 meter plot size using the center for yield and sampling. I think with 5 locations with alkaline soil would give a clear test of the hypothesis.

Myself,followers and viewers of this question will note your suggestion and I shall try to implement it is possible where ever it is possible.

I've no experiences in agriculture aspects, but these discussions give me enlightenment. Thank you. I work on sanitation technology developing   Bio-Toilet (dry toilet) using ligno-cellulosic material as matrix for feces/urine degradation. After a couple of weeks we could harvest the compost (usage matrix). It could be used as slow release P-source for the plant, I hope. But we haven't yet analyse it.

May I make recommendation to Neni Sintawardani.

In many of the composting areas the odor problem is significant.

One of the ways we have used to combat this is to use clay and gypsum which causes a reaction which builds the organic component with the clay through the mediation of Calcium.

This can greatly reduce the odor issue especially when a ratio of Carbon to Nitrogen is not below 30:1. In our composting when we have manure we use in the manure compost layer 10% by volume kaolin clay, 2% gypsum or calcium sulfate and we 1% mature compost as a source of inoculation of recycling microorganism.

Hope you might try some of these ideas and hear your response of their utility.

Dear Paul,

I used de-composted process in dry toilet (pub.attached). It's aerobic process.

Dr.Neni,good information and there is need for more such work.

Thanks Dr. Rao. Gladly to discuss it further

Dr.Hepperly,in the manure amended with clay and gypsum,there is possibility of complex  formation between humus and sulphate ion through calcium, i.e,humic-Ca-SO4.Similarly,humic-Ca-H2PO4 complex can also form,if free Ca ions are available or if phosphate can displace sulphate from the complex.If humus-Ca-Phosphate complex forms, it will prolong the availability of P in soil when manure is applied .This aspect needs further study or validation.

The issue of water quality has been related to eutrophication related to the loss of Phosphorus and Nitrogen into the global water system. The proliferation of dead zones is related to inadequate agricultural systems.

Erosion and leaching is much reduced when we achieved the stablized organoclay complex. The commplexed large aggregate is water stable and not easily lost because of its size and cohesiveness.

When Nitrogen is not lost via volatilization and Phosphorus is fixed and the the aggregated soil structure is accomplished and maintained the losses of the key nutrients are not lost but accumulate into the farming system resulting in a regeneration of the soil rather than the mere mantenance of depleted system or continuing depletion. Upward rather than downward soil spiral.

When adequate mycorrhizae are available they contribute to stablizing the aggregate structure and maximize water and nutritient relation in a stress environment. The combining of chemical, geological and biological potentials give synergism that nature has employed in its problem solving.  We need to fully employ all these tools to achieve long term conclusive solutions to these problems. 

Dr.Hepperly, I agree with you that we have to fully utilize our organic and biological systems for their best use in restoring or regenerating soil health and productivity.

I tried to look into literature on top dressing P on cereal crops especially rice in flooded conditions.One student  from Agricultural college, Bapatla,India,tested the  complex fertilizers in split application on rice but results are not clear from abstract.(original I could not see).From scanning literature I could get some points of interest. 1.In flooded soil P moves through profile much more readily ,possibly with Fe. 2.P absorption power of roots decrease with age.3.Some recommendations of top dressing of P in earliest growth stages exist.4.Top dressing of P in forage grasses is common.5.Under P saturated conditions ,as in high P soils,P  moves in waterlogged soils into sub soil.Based on these points I can assume that the top dressed P may be available to  rice crop under flooded conditions. one can not say number of splits ,doses or rates of P application,accumulation and possible losses through leaching under high P conditions and in other soils through erosion  and run off.

In Rohtas and Kaimur Districts of Bihar, rice productivity is very high. In this area farmers are applying DAP or phosphatic  fertilizers generally after 15 -20 dayr after transplanting or after first weeding and getting very good yield. 

When it comes to starter fertilizer as used in maize culture in North America the best response is to Phosphate which is applied in a band 5 cm to the side of the row depth and 5 cm below that. This allows any salt issue to  become a non issue because of diffusion gradient.

The use of starter fertilizer which is never applied at more than 200 kg/ha can give 80% of the maximum yield of broadcast upfront soil application. 

The application of the Phosphorus early stimulates early rooting. 

I believe the biggest need for the Phosphorus is upfront and below the seed to stimulate that early rooting. Ideally Nitrogen would be applied mostly at peak need at 2 about 20 cm rice height and the majority of the potassium would be applied at boot stage for its effect on maturation processes. 

For the Zinc issues the use of seed treatment and a month after application foliarly would optimize that need. 

Humic acids can be very effective in the early growth stages and the use of Humic Acid Phosphorus might be very effective. In organic production I have gotten excellent results with earthworm casting as the starter and leaf compost as the all season nutrient source. 

Some thoughts. 

Dr.Hepperly,we all understand the importance of application of phosphorus before sowing or transplanting(rice) or early in season before tillering. But in real practice farmers are applying P or PK along with N in 2-3 topdressings.Also the complex fertilizer use is increasing in place of straight fertilizers.Farmers see visible effects and also the effect in yield realization through the practice.But one has to see the resource use efficiency and economics of use of input.Also the possible environmental  affect in terms of surface water contamination.To convince the farmers we need experimental evidence to show inefficient or wasteful use of a resource.Also if there is a demand from crop in high yield environment and soil supply is inadequate, we have to see the way on how to provide P to cereal crops in heading/booting stages.Dr.Hepperly, I appreciate your other suggestions.