Unfortunately, a lot of the world's soil has been harmed by current practices and contaminated with unwanted chemicals. Hydroponic greenhouse production is one approach to extremely efficient, low environmental impact agriculture that provides significantly increased yield per area plus the added benefit of growing crops year round, which further increases the total yield per annum. In some parts of the world, they have taken this to the extreme and created vertical farms, thanks mainly to LED lighting technology. An organic and currently sustainable method is aquaponics, wherein fish waste is used as the primary source of plant nitrogen.

 Yield stagnation/decline is possibly due to loss of nutrient supplying capacity of soils,  development of pest and diseases, climatic aberration, repeated use of same cultivars over the year, lacking of crop rotation, development of allelopathy in the rhizosphere zone, development of  acidity or salinity through poor irrigation water.

To overcome such situation addition of humified organic with inorganic,  use of high yielding cultivars,   alternation of crop rotation, use of amendments to improve soil physical conditions, adoption of climate resilience crops, better quality of irrigated water etc. may possibly improve /sustain productivity.

Crop intensification is the main way that agricultural systems  respond to increasing production needs on a stable land resource. We need to get more production on less land. 

The warming of climate results in a worsening of fluctuations and greater episodes of droughts. Rainfall and its effective use is the biggest limitation to our world Agriculture.

To get better water use in world agricultural fields we need to have a goal to bring agricultural fields to 5% soil organic matter from the about 1% abounding currently in main production zones. 1% soil organic can absorb and recirculate less than 30 units water for every 100 unites dry soil the same 100 units at 5% soil organic matter can absorb and recirculate over 200 units of water.

Crop rotation needs to be anchored on a hay component that conserves and builds the soil.  For ever 2 years of row cropping we need 2 years of hay production to build up depleted soil resources.

For row crop in rotation the water will be short during some critical times. The use of varieties and crops with drought and heat tolerance will help. If our limited resource of water is targeted to critical periods of growth and reproduction better results are possible.

In the rotation the use of composted manures with straw residues will be necessary as well as better control of drainage and remedying the pH and nutritional limitations.

Dr.Chidiac,the three points mentioned by you are relevant and needs attention.It is has normally  been commented that the conventional/chemical/industrial agricultural has harmed the soil.But if one goes deep and  try to  analyze  what  real effect it has  on soil structure, soil pH and organic matter status  etc, the adverse effects   are not so clear or conspicuous in many soil- crop environmental situations.I agree with you that hydroponics made good progress and it can further progress in future.It may not be suitable for bulk production of foodgrains but may contribute  to vegetable production.Aqua-phonics using fish byproduct manure  is a good proposition but how much manure can be generated is a big question as fish waste  has several other alternate uses.Dr.Manna  I agree with your point regarding monoculture with same crop/variety without break or alternate crop in rotation which may  cause yield decline because of pest and disease emergence , drought and allelopathic effect etc.Dr.Hepperly, I agree with  you on the issues raised regarding critical role of water,soil organic matter ,crop rotations ,use of drought/heat tolerant varieties,irrigation at critical crop growth stages and use of composted manure or composted manure with straw residue.But raising organic matter status  to a higher  level in some soil environments appears to be  difficult.

One of the important way to improve/yield is the use of genetic engineering which develops crops with high efficiency towards inputs as mentioned by all these scientists. Management practices may increase to an extent but miracle doesn't happen, it can happen by improving the crop variety/breed

Crop productivity can be improved by integrated farming system (IFS) approaches as mentioned earlier like crop rotation of suitable HYVs, balanced or INM, IPM, diversified farming. IFS module should be developed for small and medium farmers since in most of the Ssian countries the land holding size is small or medium in nature. Besides inclusion of GM crops can also be considered.

You may increase the yield by improving soil health, nutrient use efficiency, water management, using efficient varieties, making plant more active by triggering their enzyme system as well as by choosing proper crop rotation and cropping system. I think, at present nanonutrients and nano-polysaccharides may play a major role in increasing nutrient use efficiency, soil health, moisture retention, soil aggregation and crop production.

Dear Dr.Tarafdar,Please elaborate your last sentence/point for the benefit of the followers

Dear Rao you many other scientists have correctly pointed out that mono-culture has become a major yield limiting factors. Under the ambient soci-economic and socio-cultural environments, it seems essential to follow integrated nutrient management and integrated farming systems based on physico-chemical characteristics of soils and irrigation waters. For this technology lot of work is to be undertaken to create awareness among resource poor and small holding farmers farmers.

Secondly, the resource poor farmers need lot of government support to adopt modern and advanced technologies for sustaining the crop or animal husbandry.

The use of nano-technology, genetic engineering and other novel interventions in agriculture will and should continue continue but unless the soil and water health are not taken care, every approach will be an optimistic promise.

To solve the current and future problems pertaining to agri production and sustainability, a multi-discipline research, extension and teaching would be imperative.  

One very important aspect that the farmers and agri scientists must keep in mind that the policy makers, policy planners and governments must be taken on board to develop political will without which nothing could be yielding positive results.

Dr.Ghafoor, I agree with all the points mentioned by you.A multi-discipline  research ,teaching and transfer of technology is must for efficient resource use and achieve higher productivity in agriculture.

Dr. I too agree with other colleagues that have contributed to your question. Meanwhile, with the level and high technology that are available now, yield can be double by adoption and breeding for high yielding crop varieties that can tolerate/resistance to those limiting crop yield both in Asia and Africa.

For instance, terminal drought is prominent in Africa, hence, drought tolerance crop can be breed for and promote for adoption. likewise, for water stresses, heat/cold stresses.

Moreover, adoption and promotion of sustainable agriculture should be paramount to all agriculturist right now and how we can complement our soil to be able to sustained our agricultural production.

Dr. Rao, scientists have brought in light very good points to be considered for the future agriculture. As there is not a single factor causing present yield stagnation, so all the factors have to be addressed. See elaboration of Dr. Abdul Ghafoor. I am of the view that some nontraditional and innovative ways or to be adapted to cross the present barrier. The use of nanotehniques, genetic engineering and many like that are presented as future hope by many researchers but some thing solid and of practical nature should emerge to change the whole scenario.

Dear colleagues, we are already using and also increasing the area under high yielding varieties.But still we need better varieties with  much higher yield potential as highlighted by Dr.Das and Dr.Rajamanickam.Another important dimension is that we have to raise productivity of our soil resources with matching new and innovative technologies/practices /products to realize the yield potential of new crop varieties as highlighted by Dr.Oluwaseun and Dr .Hussain.

when we look at the constraints the adjustment of pH and the compaction of soil stand out as issues which are known about but generally not completely addressed. Since pH affects everything it is astounding that even in the most sophisticated countries and companies theses issues are not addressed in any universal way.

Whether in developing or developed situations using hand or machine methods how many of us check the whole of our field for compaction issues.

In relation to eliminating constraints in production. I believe these issues need to met along with a complete mineral analysis and then rotation and amending strategies.

These problems can be addressed with identification time and effort but not without long term perspectives persistent effort and a monitoring system based on achieve soil goals.

It has been my own organic perspective that not even organic farmers who have a system  are not setting soil improvement goals nor diligently monitoring them even when they comply and set a long term system into production and verify its function by recording their practices.

some thoughts 

We need to follow the steps in broad spectrum

1. Better improved variety high yielding, efficient user of nutrients, disease pest resistant variety

2. Identify soil, climate and managements problems relating to low yield

3. Soil quality/health management through INM, FUE increase, SWC measures

4. Management aspects - sowing seeds in row, proper spacing & seed rate, proper time of sowing, weed management, irrigation management and other I/c operation, proper time of harvesting

5. Measures of IPM & IDM

6. Social awareness

In the recent past a lot of importance  is attached to promotion of best  agronomic/agricultural practices.Dr. Das you have nicely listed  all the possible best agricultural practices to increase not only the productivity but also to take care of soil health and environment.In each uniform area/zone of a particular crop in a particular state/country all best practices related  to seed use,fertilizer and manure use,weed control,pest and disease control cultural operations,  irrigation and drainage need to be codified ,popularized, implemented and monitored for best results ,i.e. increase in productivity.Of course micromanagement is required to take care of heterogeneity in the area.

Sir, a single strategy or technology won't work for the expected quantum jump. A synergy between technologies (superior varieties adapting to the climate change, hybrids, transgenic...), extension activities to bridge the yield & information gaps (FLDs, Field days, Village adoption....), policy governance (higher investment in R4D) and institutions is the need of the hour.

Drs Hepperly and  Ramadas and other colleagues,I agree with you that promotion  of some technologies alone may not help the countries to double their crop productivity.We should follow a holistic approach comprising the improvement in soil physical conditions ,chemical properties, biological conditions and amelioration of degraded lands. Drought management through resilient varieties, supplemental  irrigation and use of poor quality water use etc,improving soil chemical environment through pH corrections  through amendments, removing physical constraints  like compaction and poor structure through amendments,improving biological conditions through organic amendments and reclamation/amelioration of degraded soils through appropriate amendments etc are all important to improve soil productivity and raise the crop yields to higher levels.

Yes, Dr. Subs Rao, your concluding remarks are quite right.

Dear sir,

Different types of stress tolerant variety can improve yield in India. A lots of land where drought, salinity and submergence is a problem, if it is possible to introduce drought tolerant, salinity tolerant variety the yield will be jumped and a lots of fallow land will be cultivable.   

Mr.Rahman I endorse and appreciate your point.

Development of varieties/hybrids with target yield in targeted crops using molecular tools alongwith management of  soil conditions.

Shri Dhar,quite good point

Yes, point of Shri Dhar is appreciable.

Proper use of nutrient (Integration) with high yielding varieties (According to soil conditions) like drought tolerance, salinity tolerance etc. is very much important while best agronomic methods of sowing and planning of crop can make possible double/maximum crop yield. Main thing is that move yourself inventory during crop cultivation. For that my research work  on sunflower you can read from paper in publications

I feel identification of Best Management Practices (BMPs) and suitable stress tolerant varieties as mentioned Dr. Rehman is the most appropriate at this point. Soil health has became most important aspect to be focused to promote higher yield. 

This should be approached both from technical and institutional/policy aspects. On the technical side you ought to have the right kind of varieties suitable to the environment (agro-ecology) you are trying to target. The varieties of course need to be accompanied by the right kind of crop management.

Then comes the policy issue. Engage your policy makers to create the right environment for the crop. This includes several aspects: e.g. input (seed, fertilizer, pesticide), supply, market, etc.

I humbly invite you to read our recent paper on maize in Ethiopia "Factors that transformed maize productivity in Ethiopia"

Dr.Abate I will go through your paper

Use of genetic diversity in the breeding program and agronomic innovations for crop management would solve your problem. I don't believe on stagnation because we cannot explore or exhaust the genetic diversity's even 1% in our whole life. 

There has been substantial work on the role of environmental and genetic components on the performance of agricultural crops. In crops like maize and soybean the increases from a traditional to intensified crop system has shown about 50% is from genetic improvement and about 50% from agronomic practice or cultural intensification. When we look at feeding our growing population it is important to understand both cultural practices and breeding will lead to improvement. The big missed component has been the lack of focus on soil status and improvement. This probably is a function of the difficulty of wondering below the surface. This is a notable deficiency since in a world of global warming the ability to counteract that issue is vested in the unseen world of plant roots and the microbiology of the soil environment. In that respect the vast majority of soil microbes are not even described. Below the earth surface is the last frontier.

Several colleagues(Drs Bhatti,Ali,Rehman  and Dhar)highlighted the role of crop improvement in raising the crop yield.Dr.Abate  and others stressed  the crop management .To realize the yield potential of varieties we need to improve the soil productivity by paying attention to soil status and exploiting the great role of organics and soil microbes as pointed by Dr.Hepperly. Also equally important  is good policy support and transfer of technology efforts through extension personnel.I invite any other innovative approach/idea

Hello. Worldwide, yield increases are significantly related to 3 things; genetic improvements, agronomic changes and CO2 fertilisation. The latter is quite important; here in Australia, about half of the yield improvements attributed to genetic changes have subsequently been shown to be due to CO2 fertilisation. 

Agronomic changes that increase yield are being supported by reductions in the prices of N and P fertilisers. Oil prices will continue to affect the affordability of fertilisers, and the future of prices are difficult to predict.

Finally, I want to reflect on the assumptions that you have made concerning the demand and need for food. Currently, world food supplies to humans account for more than double the need for calories and almost double the need for protein. There is also a significant amount of food suitable for humans that is fed to animals at a net loss of calories and protein. It is clear, but rarely reported, that our current global rate of increase of food production, in combination with quite small reductions in food wastage and land degradation are sufficient to feed the projected maximum human populations of 10 to 14 billion in the middle of next century.

I look forward to a time when discussions of food supply and  security are more realistic and thoughtful. In particular, it does a great disservice to science to propose naive, one-dimensional solutions such as genetic improvement or increased soil organic matter. In the age of the Internet, there is no excuse for being ill-informed on such topics.

Best wishes in your investigations and where they take you.

Dr.Robinson,I welcome your critical comments.I am not clear on how to make CO2 fertilization real under farmers' conditions (except for utilizing already available CO2 in the atmosphere). Please give some more details .Lot of cereals are now being utilized for converting carbohydrates(cereals) in to protein through animal system.How to change the food habits of people in North America and Europe.Also , people   even in developing countries on attaining certain economic status are going for non-vegetarian diets .Can You  suggest/provide a reference which predicted drastic changes in food habits of people across continents in the next 35 years or so?.Big question is how to save food in North(with dietary changes) and use it South.Even if it is possible then how to purchase the food?Poor people in the same country are not able to purchase food without subsidy.So every country wants to be self sufficient in food grain production,to a level possible.

Hello again. Regarding CO2 fertilisation, I am not suggesting active management. However, the future yield benefits are significant. Also, cropping at high latitudes will be more productive with enhanced greenhouse effects, mainly due to longer growing seasons.

As you say, an important aspect of food security involves food transfers from north to south and rich to poor. This is happening now due to excess production of wheat, corn and other grains resulting in maximisation of the northern stockpiles and consequent low prices in the international markets. The price concerns of just a few years ago are a distant memory. Wheat, for example, is three to four times more affordable in China now than in 2010. By 'affordable' I'm referring to the ratio of income to price. 

It is counterintuitive, but true, that in low-income countries the move of people from poor rural areas to jobs in cities is increasing, not decreasing food security and resulting in more nutritious diets. It is clear that over the last 100 years in high income countries that total yields have gone up while the number of farmers has declined strongly, and food security has increased strongly (mainly because income have increased due to NON-FARM increases in GPD per capita).

Thanks for your reply. It is all very interesting.

 Hello, For my experimental. I can improved the rice such as Hom Mali Rice by organic fertilizer and prevent insect by wood vinegar. I take a silicon fertilizer for protect the blast that case disease and reduce yield. Then, you can apply this method to your plants for improved the yield.

 Thank you Robinson for your further comments.Even with all our best efforts in India still 50% of people  relay on agriculture for their livelihoods.Situation may not be better in our neighboring countries and Africa.So,despite of surplus  grain production in North America and Australia etc. still we have to raise our crop production.I request colleagues to suggest innovative ideas for raising crop productivity.

Dear Wanida

The role of Silica is particularly salient in crops like rice. Rice is used as the staple crop for about one third of the Worlds population. The Silica content of soil is seldom assayed but when less than 1 ppm response to amendment can be expected.

Silica deposits in the walls and around the ingress of plant pathogens such as blast and brown spot, decreases the digestibility in relation to chewing insects. In addition it is now shown that phytoalexin synthesis may be compromised with deficient Silica. In terms of de silicanization it appears prevalent in ultisol and oxisols which are older soil families which develop where precipitation is greater than evaporation causing soil depletion.

Silicate in the soluble form also alleviates Phosphate fixation the exact mechanism is not clear to but P and Si are both about as the element with 4 oxygen atoms.

Check out the work of L. Datnoff for a review of Silica applications. I believe there is probably a need to get silica readings particularly in acid tropical soils.

 Dr.Hepperly,Ms.Wanida,raised a new issue of silicon and you have nicely elaborated the same with good example of rice.In the recent past some new review articles and new awareness about silicon have emerged.Can any body provide further information on silicon nutrition in other important crops.and conditions under which silicon nutrition  is important.

When we are making sustainable plans for our farms, we need to assay and utilize the local materials biological and mineral that are available.

When testing out the ability of clay to reduce issues in compost nutrient losses I developed a collaboration with Alcoa which has alkalinized Clay as a by product. The Rodale Institute would not accept the import of this material so I used subsoil clay which is readily available.

The inclusion of clay with gypsum and humic acid greatly reduced the losses of nutrient and reduced salt issues from the raw manure component. If we have a sandy soil the use of local clay and Calcium resources can promote the stabilized organic matter resource and thereby the capture and retention of water which is the biggest constraint in our global agriculture.

If we have a clay soil the use of local sand which can be used in the compost will be useful as it will help the physical nature of the soil but the biology of the compost microbes will solubilize Silicates. I could envision this for your rice paddies in areas which are deficient in Silica. The Silicon was shown by Datnoff in Florida to be able to combat blast at the same efficacy as Benlate Fungicide. When we balance plant nutrition we can greatly decrease the damage from diseases and pests.

Dr.Hepperly,I agree with you that our science should be build or based on local knowledge and resource base to have more practical utility to farmers in those areas.

when we attempting to maximize our intensive cropping we need to dig a pit and look to physical structure of the soil and presence for compaction. We should accumulate backgrounds studies and interview local experts. The use of penetrometer is useful. We should eliminate constricted layers and develop a comprehensive soil conservation plan. Structural condition and drainage are often not fully considered. One of the chief ways yield and quality is addressed is by installing and improving irrigation systems.

Dr.Hepperly you have raised an important issue ,i.e compaction.As I understand there is less work under Indian conditions on compaction.We can measure compaction using penetrometer. Next step is how to treat the compacted soils ?What management options are available?How to improve aeration  and drainage in soils is also important.

Dr Rao

There are several options for dealing with compaction. Biologically the use of taprooted crops can break through compacted layers. In addition the use of rippers can mechanically work to provide root channels and in addition the crop system can avoid repeated compacting practice by permanent bedding that restrict traffic zones. I think there a potential chemical interaction related to optimizing Calcium content and remediating salinity which can be involved. This is a gap in research around the world a fertile area of development.

Some thoughts. Paul

Dr.Hepperly ,thank you  for providing good information/technologies and  also highlighting the need for more research.

Dear Doctor Rao

In terms of the Phosphorus questions the synergism of legumes through Rhizobia stimulate the mycorrhizal system the stimulated to mycorrhizal fungi  promote Rhizosphere communities of fungi and bacteria that have Phosphorus mobilizing capacity the plant, bacteria and fungi work together synergistically when the system is optimized for them.

These synergistic symbiotic approach required distinctive nutritional support  aimed at supporting the symbionts for the synergism to be most effective. They are especially dependent of micronutrients such as Mo Co and Zn to be most effective and need to evaluated much more thorough.

Symbiotic synergistic is a way of getting more for less and changing negative environmental and energy footprints into positive ones. These solution are systematic in their nature and need interdisciplinary collaborative focus and coordination.