Please help me understand organic VS convention nutrient sources

[footie]

Dear farming community,

I'm a student and am working on a project in which I need to understand the different nutrient inputs for an organic VS conventional fruit and vegetable farming assignment. So I've got 2 short questions if any of you would be so kind to help me out here, feel free to answer the questions even just literally with approximate percentages as I trying to understand how much is used....

1. Organic cannot use chemical based nutrients so uses manure and crop rotation. Approximately, what percentage of nutrient needs are met on average from manure and animal sourced nutrients alone? For example, do most organic farmers rely on close to 100% manure and blood/bone/feather meal or is it more like 50% manure and 50% of the nitrogen comes from crop rotation? We're talking in broad approximations here but if there is a huge difference between for example potatoes and cabbage, I'd be interested to hear!

2. Most people think that conventional farming mostly uses petroleum/chemical NPK but I am seeing that way more conventional farmers are using manure now because of the trace nutrients and it's supposed to be better for the soil. What sort of percentage of manure do conventional fruit and vegetable farmers use on average nowadays? For example 60% manure and the rest with chemical based fertiliser...? Or is that figure way off?

Thanks people!

 

[farmerm]

Conventional farmers have always used animal waste manures where available, there just isn’t enough to go around. To produce more muck you need more livestock which requires more feed which requires more land which requires more muck.... some crops on some farms will use a high proportion manure others have none

 

[footie]

Thanks for getting back. So if I understand you correctly, muck is preferable and the only reason why you would pay for chemical NPK is if you don't have enough, or have access to manure? Manure is cheaper as well right for the same amount of nutrients?

 

[cows r us]

Thanks for getting back. So if I understand you correctly, muck is preferable and the only reason why you would pay for chemical NPK is if you don't have enough, or have access to manure? Manure is cheaper as well right for the same amount of nutrients?

Most farmers in the uk are in nitrate vunerable zones, this means that we are limited In the amount of manure we can put on the land. If you get a copy of rb209 it will tell you how much of each nutrient a crop needs and how much different manures can supply. There are so many different farming systems and soils to give you an answer really. Farmers use manures, cover crops, digestate, manufactured fert, seaweed, legumes, biology, rotation and a whole lot of other things to supply their crops with nutrients.

 

[farmerm]

you can find RB209 here.... https://www.ahdb.org.uk/knowledge-library?q=rb209

 

[footie]

thanks people, this document is really helpful!

 

[farmerm]

Thanks for getting back. So if I understand you correctly, muck is preferable and the only reason why you would pay for chemical NPK is if you don't have enough, or have access to manure? Manure is cheaper as well right for the same amount of nutrients?

Idea crop nutrition comes from a mix of manure and manufactured fertiliser. Manure has other physical benefits over bagged fertilisers, it provides a source of food for soil organisms that improve soil structure and nutrient cycling. Nutrient release from applied manure alone doesnt always match well with crop demand, even with sufficient P and K most crops benefit from applications of N+S during peak growth which is not adequtely provided from manure applied prior to planting in the Autumn.

 

[ollie989898]

Steady on.

The good thing about inorganic fertilisers is that they work. The quantities being applied are known, empirically, and tested. They have to be to meet the trade descriptions act. They are a good fit where the crop has an identified need and it must be met quickly and reliably.

That doesn't mean organic manures or similar don't work; they certainly do. But a manure is not always a homogeneous material- the moisture content can vary, the carbon to nitrogen content may vary, the actual nutrient composition can vary. Also, most forms of organic nutrient are in a variety of forms: in pig slurry, for example, you might have pure ammonia, you might have a bit in nitrate form, you might have some in nitrite form, and some might be locked up in an unavailable form that will break down over time in the soil and become available later on.

Of course manures are good for the ground; you are returning organic matter, a host of additional micro-organisms and also the above multitudes of nutrient sources mean there are on-going benefits as the soil can drip feed the crop throughout the season giving better plant health and survival in say the cold winter months.

 

[Brisel]

I'm a conventional arable (sorry, no fruit or veg) farmer and use as much manure as I can get, which isn't a lot. I'd say that less than 8% of my N is derived from manures including sewage cake, compost, horse muck and farm yard manure (FYM). The figure will vary widely but an intensive conventional dairy farm using their slurry & FYM efficiently will be at least 40% muck derived.

 

[Barleycorn]

Most organic farmers get much of their N from legume rich leys which are either grazed / conserved, or grow a 2 to 3 year fertility break and plough it in. Cow manure is very valuable though, gets the right bugs in the system. We compost all our stackable manure and spread it thinly.
It is possible to use PAS100 green waste compost, but it's very low in N (and full of plastic).
You might be interested in searching for Iain Tolhurst, he is a market gardener who gets his fertility from composted woodchip, as well as a good rotation and fertility breaks. Our vegan friends aren't too keen on crops grown with animal manure, prefer to use fossil fuels to produce artificial fertilisers.

 

[yellow belly]

If manure is from a conventional livestock source can it be use on an organic farm without loosing organic status

Manure sources do have a bigger potential nutrient loss as the n is slow release so more is available during the wetter months when n is lost through excess rainfall
Inorganic n is aplied in spring when crops utilise it and in a high yielding crop more n can be in the harvested crop than put in as fertiliser

From virgin farmed land wheat can be cropped without n for 30 to 50 years before n is needed to be added

 

[Barleycorn]

Not quite right about the manure on organic farms. You can only use it from unintensive systems, and then it has to be either stacked for a year or actively composted for six months. I know, as a few years back I was offered some 'organic' chicken manure. When I asked for the paperwork it turned out to be from a red tractor free range set up, so we composted it.

 

[Al R]

No @yellow belly you can’t use conventional manure on organic land incase the animals were fed GM.

@ollie989898 and @Brisel have summed it up, except the main problem with manures etc is the compaction and spreading widths. A 30-34t tractor spreader and manure load will be travelling every 12metres maximum to cover accurately, they also can’t go very far before they run out.
A tractor fert spinner and the artificial fertiliser typically wouldn’t weigh much more 12t and you could spread that at up to 36metres wide, double the speed of the manure spreader and cover 20 times the acreage with far lower compaction.

Having ran conventional arable farms and now on a organic mainly sheep but a bit of arable farm there are situations where best of both works well but not to be totally reliant on 1. After 20 years organic all of my K index’s are 1’s yet PH and P have risen quite a bit, yields are very close to conventional for cereals but grass isn’t quite as good even though we’re now running more clover in the leys as opposed to straight Italian ryegrass when we had a lot of potatoes.

 

[footie]

thanks people, this is quality information!

 

[glasshouse]

thanks people, this is quality information!

After the sewage systems were installed in all the major cities around 1870 to 1900, all the human waste was put out to sea and wasted.

This has resulted in serious impoverishment of arable soils in eastern britain.
Since about 1995, all this sewage is going back on the land, but without much nitrogen, so N is still required.

 

[glasshouse]

Serious reductions have been seen in seabird numbers, i would say thats because the crap is not feeding the sea anymore.

 

[Bogweevil]

Most organic farmers get much of their N from legume rich leys which are either grazed / conserved, or grow a 2 to 3 year fertility break and plough it in. Cow manure is very valuable though, gets the right bugs in the system. We compost all our stackable manure and spread it thinly.
It is possible to use PAS100 green waste compost, but it's very low in N (and full of plastic).
You might be interested in searching for Iain Tolhurst, he is a market gardener who gets his fertility from composted woodchip, as well as a good rotation and fertility breaks. Our vegan friends aren't too keen on crops grown with animal manure, prefer to use fossil fuels to produce artificial fertilisers.

pretty sure most vegan crop production protocols are organic which rules out synthetic fertiliser as well as animal manures/fertiliser, leaving them with cover crops and legumes. Legumes fit well in vegan diets but other than that there is only seaweed (an excellent fertiliser) and all the rather doubtful minerals such as granite dust and good luck with that