Cover crop vs Biosolids

[JD6920s]

You need to value the total P; they are only telling you 50% of it is available which isn't quite correct. If your soil is P index 0 or 1 then only use 50% of the total P in the sludge as the figure you use in calculating fert requirement. The other 50% will be picked up the next time you soil sample. If soil P index is 2 or above you are supposed to use the total P figure in your fertiliser calculations. Basically your not losing half the applied P, you just take a cautious approach where the soil is deficient i.e.. P indices 0 & 1.

You analysis shows 336kg/ha of Phosphate (assuming its phosphate and not phosphorous, if its phosphorous the phosphate equivalent will be even higher). With TSP at £268/tonne that makes a kilogram of phosphate worth 58p/kg, so your 336kg is worth £195/ha.

Its going to cost you £65/ha to bring £195/ha of phosphate onto the farm. Don't forget the 25kg/ha of N too. On purely fertiliser terms its good value.

That makes it sound a lot better!

And also the sulphur element has to be taken into account, though if sludge is applied in the autumn preceding a winter wheat, would that have any benefit or would it have leached away before take up in the spring?

 

[N.Yorks.]

That makes it sound a lot better!

And also the sulphur element has to be taken into account, though if sludge is applied in the autumn preceding a winter wheat, would that have any benefit or would it have leached away before take up in the spring?

Good question. Read the last page of this:

https://cereals.ahdb.org.uk/media/357116/is28-sulphur-for-cereals-and-oilseed-rape.pdf

 

[Brisel]

The microplastics issue is an interesting one. I saw the Countryfile piece & thought it raised more questions than answers. Who is going to do this research? I'm sure the EA will be keen but the biosolids producers will want to keep it quiet.

What is the cost of compaction, heavy metal and microplastic contamination? What is the benefit of organic matter and cheap phosphate/micronutrients? In future, I'd like to stop importing organic matter to save cost, contamination risk and minimise traffic and rely on unlocking the thousands of tonnes of phosphate I have in the high pH soil already but right now I'm shipping in everything I can reasonably get to boost SOM and mineral reserves to keep the soil/plant biology fed.

Attached is the nutrient analysis results for proposed spreading this summer here. @TopBanana are you supplied by Wessex Water?

 

[N.Yorks.]

The microplastics issue is an interesting one. I saw the Countryfile piece & thought it raised more questions than answers. Who is going to do this research? I'm sure the EA will be keen but the biosolids producers will want to keep it quiet.

What is the cost of compaction, heavy metal and microplastic contamination? What is the benefit of organic matter and cheap phosphate/micronutrients? In future, I'd like to stop importing organic matter to save cost, contamination risk and minimise traffic and rely on unlocking the thousands of tonnes of phosphate I have in the high pH soil already but right now I'm shipping in everything I can reasonably get to boost SOM and mineral reserves to keep the soil/plant biology fed.

Attached is the nutrient analysis results for proposed spreading this summer here. @TopBanana are you supplied by Wessex Water?

Why are you spreading at 18t/ha, this puts you a long way under the nvz total N threshold? Is this your choice or theirs? Does it have something to do with the P indices of the receiving soil?

 

[Brisel]

It usually ends up being 20 t/ha by the time they've diverted a few extra loads in. Still under the 250 kg/ha N limit though. Their policy not mine. They won't spread over P index 3.

 

[JD6920s]

Why are you spreading at 18t/ha, this puts you a long way under the nvz total N threshold? Is this your choice or theirs? Does it have something to do with the P indices of the receiving soil?

It's all according to the N in the product, we have in the past had 26t/ha, 23t/ha and this time 20t/ha and I have heard of some having up to 33t/ha

 

[Brisel]

What is the total N in yours? 240 - 250 kg/ha?

 

[JD6920s]

What is the total N in yours? 240 - 250 kg/ha?

245.20 kg/ha

 

[TopBanana]

The microplastics issue is an interesting one. I saw the Countryfile piece & thought it raised more questions than answers. Who is going to do this research? I'm sure the EA will be keen but the biosolids producers will want to keep it quiet.

What is the cost of compaction, heavy metal and microplastic contamination? What is the benefit of organic matter and cheap phosphate/micronutrients? In future, I'd like to stop importing organic matter to save cost, contamination risk and minimise traffic and rely on unlocking the thousands of tonnes of phosphate I have in the high pH soil already but right now I'm shipping in everything I can reasonably get to boost SOM and mineral reserves to keep the soil/plant biology fed.

Attached is the nutrient analysis results for proposed spreading this summer here. @TopBanana are you supplied by Wessex Water?

With Cover Crops having the potential to add significant biomass and capture nutrient with subsequent return they do look more of a better option. Plus you highlight the compaction issue from heavy traffic and having little control on application.
Does anyone have an estimate of what a Cover Crop puts back into the ground both in terms of nutrient and biomass (tons/ha), it would make for a good comparison.

 

[N.Yorks.]

With Cover Crops having the potential to add significant biomass and capture nutrient with subsequent return they do look more of a better option. Plus you highlight the compaction issue from heavy traffic and having little control on application.
Does anyone have an estimate of what a Cover Crop puts back into the ground both in terms of nutrient and biomass (tons/ha), it would make for a good comparison.

The cover crop is only taking nutrients from the soil and returning them again once its destroyed and incorporated back into the soil. So your not actually boosting soil nutrients. The mineral nutrient that is taken up by the CC is converted into organic matter that will be broken down in the soil and will eventually end up in mineral form again. Its cyclical.

If you are needing to boost soil nutrient concentrations you'll need to import nutrients into the soil via fert or manures.

The CC can assist in grabbing some nutrients that may be leached, thus cutting down on nutrient losses.

I did analyse a cover crop that was due for destruction earlier this year. Note that it was only the above ground vegetation analysed not the root mass.
The above ground CC weighed 1.012kg per 1m sq. This equates to 10.12 tonnes of CC per Ha.

Nutrient supply from the CC was:

Total N = 46.552 kg/ha
Total P = 5.141 kg/ha
Total K = 78.734 kg/ha
Total Mg = 2.459 kg/ha

I can't remember the plant species mix, as this will probably influence the nutrient. This particular mixed CC was effective in recycling N and K.

 

[martian]

As N Yorks points out, cover crops won't capture much beyond a bit of nitrogen from the air, apart from CO2, of course, which is the building block for biomass creation. But, by fostering continally growing roots in your soil, you are providing incentives and nourishment for microbes and fungi around the roots, especially mycorrhizae fungi which can extract otherwise unavailable minerals, in particular Phosphorous, and swap it with the plants in exchange for sugars formed in the plant's leaves. This is not something that will happen overnight, or in one years cover crop, but then we should, famously, be farming as though we'll live for a thousand years and so take the long term view.

 

[TopBanana]

More of a slow burn approach rather than treating a deficiency with an application of Biosolids. Thanks for the input, I had thought CC added more than the took away. The benefits of preventing nutrient wash are well known, the added root structure is a big plus point to me, I think our soil would hugely benefit from the added structure.

Hadn't considered the influence on mycorrhizae and then soil life. Adds a little more to the argument of CC. Thanks for the interesting replies,all adds value to the discussion.

 

[Old John]

The cover crop is only taking nutrients from the soil and returning them again once its destroyed and incorporated back into the soil. So your not actually boosting soil nutrients. The mineral nutrient that is taken up by the CC is converted into organic matter that will be broken down in the soil and will eventually end up in mineral form again. Its cyclical.

If you are needing to boost soil nutrient concentrations you'll need to import nutrients into the soil via fert or manures.

The CC can assist in grabbing some nutrients that may be leached, thus cutting down on nutrient losses.

I did analyse a cover crop that was due for destruction earlier this year. Note that it was only the above ground vegetation analysed not the root mass.
The above ground CC weighed 1.012kg per 1m sq. This equates to 10.12 tonnes of CC per Ha.

Nutrient supply from the CC was:

Total N = 46.552 kg/ha
Total P = 5.141 kg/ha
Total K = 78.734 kg/ha
Total Mg = 2.459 kg/ha

I can't remember the plant species mix, as this will probably influence the nutrient. This particular mixed CC was effective in recycling N and K.

But the cover crop is harvesting energy from the sun and capturing carbon from the atmosphere. Legumes also capture Nitrogen too, so it IS adding something more than just stopping stuff from leaching away. Some things, like oil radish, root deep and bring up nutrients that are below most crop roots.