Nutrient cycles in organic agriculture are not fully sustainable. There is need to give emphasis on building of high organic matter and further reduce losses through adoption of conservation agriculture practices. Further to stop leaching losses of nutrients appropriate irrigation method and efficient drainage system at farm level is needed.

@ Simon, the three main cycles of an ecosystem are the water cycle, the carbon cycle and the nitrogen cycle. These three cycles working in balance are responsible for carrying away waste materials and replenishing the ecosystem with the nutrients necessary to sustain life. Organic agriculture helps all the three cycles only thing the mineral concentration under organic is low. That can be improved through other sources i. e. by chemical or nano-nutrient sources. At the present moment, i think, organic agriculture along with some chemical inputs would be the sustainable solution.

We have experience with fruit crops , while fulfilling the nutrient requirement of fruit crops like citrus na dbanan , the potassium requirement is difficult to fiulfill through organic sources , unless supplemented with othe rinorganic sources. Yes, in a organic production system , nutrients are cycled in a much efficient way compared to inorganic production system , for the simple reason , accountable to better rhizosphere micorbial environment . as far as depleting the the nutrients of geogenic origin is concerned , this again has to be seen in the context of checks and balances of nutrients added versus removed. ..

The intensity and frequency of tillage, plowing and other mechanical operations to prepare the soil for planting are (in my opinion) the quick answer to your question. Tillage produces erosion and with it soil nutrients lose residence by being washed away. Among these soil carbon in the form of humus is most detrimental loss because carbon in SOM acts as a sponge holding soil water and nutrients thus fostering microbial activity and metabolisms that contribute effectively to soil fertility. Employing perennial plants in agriculture like we see in agroforestry systems facilitates residence of soil nutrients in the soil.

For the N-based fertilizers, organic farmers grow legumes to optimize the soil. Additionally, manure and compost in organic agriculture are not solely sourced from crops. Organic farmers use livestock dung and excretions to produce nutrient-rich organic fertilizers. This can effectively recycle availability of nutrient within the farming system. The basic concept of organic farming and/or sustainable farming is to ensure the balance of resource outputs and inputs.

Nutrient cycles in organic agriculture are not fully sustainable. There is need to give emphasis on building of high organic matter and further reduce losses through adoption of conservation agriculture practices. Further to stop leaching losses of nutrients appropriate irrigation method and efficient drainage system at farm level is needed.

Nutrient cycles in organic agriculture may be sustainable. By growing legumes whether in monoculture or mixed system and using organic fertilizers it can be sustainable. But it will be more wise to combine the whole system with organic mulch to increase the activities of soil engineers especially "termites".

Basically you understand it well. However, our experience with green manure/cover crops around the developing world has taught us that phosphorus lasts a lot longer than one would expect. This happens for several reasons. Smaller agricultural plots are not closed systems--birds, bats, and other animals distribute nutrients through the environment, in larger quantities than most people realize. Secondly, if crops are fed through the mulch (as a tropical forest does), virtually no P ever touched the soil, so there is very little tie-up. Third, in conventional ag, only about 1/10 of the P applied is used the first year after it is applied, and a little less each year thereafter. But with gm/ccs intercropped with annual crops, the average time any P is taken up into a crop, dropped on the ground, and then taken up again is 12 months or less. That means that each atom of P produces about ten times as much biomass as it does in conventional ag. So a very little P can last a long time! For more details, see the 2nd edition of my book, "Restoring the Soil," available from Amazon. In general, to best manage nutrients with smallholder farmers, we try to "imitate the forest," which you can read about in the paper, "Case Studies in Regenerative Agriculture," available here on Researchgate.

Nutrient cycles in organic agriculture are not fully sustainable. The organic agriculture in our geographical situation needs to address commercial organic agriculture to sustain productivity, production, and farmer's income. To make nutrient cycles sustainable, we need to go for permitted external provisions including nanoparticles to make the nutrients in balance and sustainable proposition as provisions available or we need to make provisions scientifically keeping national and international standards and organic laws.

Organic agriculture might be the ideal consequence of all agricultural practices in the context of human and soil health as well as environment. Soil is the biggest laboratory in the universe where thousands of reactions and activities are commencing in a second. Incorporation of any organic or living being /organisms to the soil makes it healthy and sustainable. All cycles like carbon, nitrogen, phosphorus etc. cycles occurring in the soil usually boost up or take place in a balance while the soil enriches with organic matter that can also be referred to as organic agriculture.

Simon Blotevogel

The Amount of nutrient harvested by the crop to get the optimum yield from the soil. This depleted amount of nutrient is supplemented by the organic manure and other organic sources it remains a sustainable, so here the important question is from the organic source need to supply to make the balance in order to achieve the sustainability of nutrient cycle in the soil.

yes, mixed culture systems and the possibility of using substances that increas the effciency of organic fertilizers such as zeolite are useful for more sustainability.

All agriculture is depletion of grow land and enrichment of dumping site(where poop and urine are dumped)

Nitrogen is recycled by fungi in the soil by promoting nitrogen fixing bacteria(they do so from the air), also protein from animals and plants is decomposed to become nitrogen, carbon, etc.

Microelements are attained from rocks of said minerals. Naturally found in all parts. Some elements more than other. But plants have been known to adapt over generations to depletions in soil. But eventually, all forests turn into desserts and form again after millions of years of decomposition attained by fungi.

Organic farming can be sustainable if feeding the immediate society near the farm and collecting decomposable waste and composting it into a form easily absorbable by the soil.

For your calculations:

1) run soil test analysis of elements.

2) Calculate element requirement by each plant you want to grow.

3) divide elements required by each plant(average if different species involved) by the total elemental composition of all the soil(soil analysis x area of land)

this will give you number of plants. Then divide this by time required to grow each batch of plants. This will tell you, theoretically, how long will it take your land to completely deplete.

Point to remember- If calcium runs out, few other minerals will have absorption problems. Thus, calculations need to consider the upper limit of present element by the limit of the element essential in the smallest quantity. Because, without that, other elements cannot be utilised.

No, it depends on how you manage

Nutrient cycle in organic agriculture is sustainable may be or may not be because agro climatic conditions is different for different situations and sustainability doesn't mean its for infinite time but it one which attain its expected life span with spatial and temporal basis...

Before thinking agricultural systems it is useful to consider that many soils largely result from the geological subsoil alteration (weathering). Rocks chemical components spectrum may show deficiencies in one or several bio-elements (eg boron, phosphorus, magnesium, copper, ...), those deficiencies are known as "primary deficiencies". In desert sands there is no life (plants, microbiologic organisms,...), there is no phosphorus, no zinc, ...nor or very little nitrogen mainly life-dependant. It is impossible to develop life without importing bio-elements for at a minimum starting the process. Also, it is impossible to care a primary deficiency without importing the missing element(s) as "fertilizer" be it organic or mineral. If on that "cured" soil, a production is totally or partly exported and taking account the as weak as possible but unavoidable losses, the soil will impoverish, plant production and global life activity decrease, and agriculture has to compensate by adding again the missing elements. Good agriculture - be it organic, biodynamic or conventional - has to - and is able to - manage such situations, improving the bio-availability, enriching the content and reducing losses for the elements existing in the soil, and bringing just enough for the deficient elements. It is also necessary to take in account the specific (ie linked to the species) needs for bioelements (nutrients) and for soil physico-chemical conditions (pH, water, redox, ...),

Dear Dr. Simon Blotevogel

In my view, some nutrients are depleted in any agricultural ecosystems over time. In other words, there is no complete recycling of nutrients because of nutrient losses through harvesting of the crops (crop removal), soil erosion, and leaching losses. It is particularly true for P, whose primary source in the soil is apatite, a mineral that is not abundant in most rocks. For K, it is not as critical as P since there are several primary minerals (feldspars, mica, etc.) that serve as a source of this element. But of course, the rate of P and K depletion depends on the stage of development and parent rock of the soil.

From my field experience - Yes!

It all depends on the management practices adopted in a particular organic farm

Yes but it depends on the soil conditions and practices we do and the environmental condition.

Nutrient cycles in organic agriculture sustainable . This is what our forefathers know since long.Recycling of the organic materials leads to sustainability.