We did have to and still do in places. I like to think that one day we'll be able to stop, but where you've got a lot of clay and a lot of rain you have to get rid of the excess somewhere. Having said that, the only places that appear wet this year are where the surface infiltration has failed due to rain impact on bare ground, dig down and the lower levels are nicely moist rather than sodden, so there is nowhere on the farm which looks like it needs moling this year.
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Feldspar
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And do you find that the moling makes drilling difficult or not?
Feldspar
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I have done the same. You think that the field is totally saturated, but in reality it's only the top layer. The increase from increase in infiltration capacity from 0.5" to 8" of rain per hr in Gabe Brown's fields should be more than the effect you get from moling.
That said, particularly where the moling can be done before a transition into no-till, then definitely we will do it. Otherwise you fail to get the basics that Dwayne Beck says need to be in place before buying a no-till drill. We're busying ditching the fields with obvious drainage problem to satisfy those pre-conditions.
Feldspar
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Now at the bit where KN talks about the inefficiency of applied synthetic N and P. She says that product is only 30-50% efficient in the case of N, and only about 10% efficient in the case of P. She recommends marching off to the fertiliser sales people to ask for a discount given that only a fraction of their product actually works.
My understanding was that the other 50-70% of N (or the other 90% of P) is not wasted. A lot of that N is used by soil biology and enters the soil food web. I'm not sure that I've read the same for P, but it is topping up the total amount of P in the soil. As much as soil biology can release and cycle P, as far as I know there are no organisms that can fix P or create it out of something else.
So whilst it is annoying that so little of applied N is utilised by the plant, I'm not sure the picture is quite as bleak as she makes out.
My understanding was that the other 50-70% of N (or the other 90% of P) is not wasted. A lot of that N is used by soil biology and enters the soil food web. I'm not sure that I've read the same for P, but it is topping up the total amount of P in the soil. As much as soil biology can release and cycle P, as far as I know there are no organisms that can fix P or create it out of something else.
So whilst it is annoying that so little of applied N is utilised by the plant, I'm not sure the picture is quite as bleak as she makes out.
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shakerator
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I think the "soil bank account" way of thinking about soil nutrients and OM in terms if nitrates not taken up there and then is flawed. Does chopped straw + N = organic matter . No
Nitrates are more "efficient" in hydroponic systems where biology is excluded. In more natural systems they may be "detoxified" out of the system
Feldspar
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Foth and Ellis (1988) reported that between 10-40% of applied synthetic N was converted into soil organic matter (not clearly defined); Stevenson (1986) reported that the residual N in soil is relatively unavailable to plants during the second growing season and availability decreases even further in subsequent years because of conversion of N into stable humus forms.
So I don't think that the % of synthetic N applied that doesn't make it into the crop that year is all completely wasted. I think that's an over pessimistic view.
dontknowanything
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There is the school of thought that artifical N actively destroys SOM. I seem to recall (but could be mistaken) that @Simon C is a believer in that one.
Feldspar
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Yes, I've heard that from Mike Harrington.
dontknowanything
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Personally I think it's probably one of those things that is "true" in that it happens in the lab. However, in the real world the increased biomass produced from added N will outweigh it handily. In fact, looking back, I wrote about exactly this, and an experiment demonstrating the same:
http://thriplow-farms.co.uk/2015/03/03/day-62-pasture-rotations-som/
"We’re often told that adding artificial nitrogen fertiliser destroys organic matter, and I’m sure that’s true. In a lab. But in the field it is clear in this experiment that the opposite happens. That’s because with the fertiliser there is hugely more crop residue going back into the soil. That benefits not only the SOM levels, but also massively increases resistance to soil erosion."
Feldspar
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That's quite well written and informative (highest compliment you're going to get). I will do some more research on this.
dontknowanything
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I'm quite grateful
Feldspar
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Lifted from this paper:
http://www.sciencedirect.com/science/article/pii/S0065211305880046
Munoz et al. (2003) studied N budget after multiple applications of dairy manure and concluded that during the three year study period, an average of 18% of applied manure 15N was recovered in corn silage and 46% remained in the soil. Unaccounted for 15N (36%) was assumed to be lost mainly by NH3 volatilization and denitrification. These authors also reported that most (82%) of the 15N remaining in soil was present in the top 30 cm, irrespective of frequency of manure application.
A complementary use of organic manures and chemical fertilizers has proved to be the best soil fertility management strategy in the tropics (Makinde and Agboola, 2002). Well decomposed farmyard manure contains about 12.9 g kg1 total N, 1.0 g kg1 available P, 4.5 g kg1 exchangeable K, 10.8 g kg1 exchangeable Ca, and 0.7 g kg1 exchangeable Mg. (Makinde and Agboola, 2002).
Organic manure has a greater beneficial residual effect on soils than can be derived from use of either inorganic fertilizer or organic manure applied alone. Combined applications of organic manures and inorganic fertilizers were found best for intercropping sweet potato (Ipomea batatas L. Lam) and corn (Eneji et al., 1997), and for intercropping cassava and soybean (Makinde and Agboola, 2002). Furthermore, nutrient use effciencies have been reported to be increased with complementary applications of organic manures and chemical fertilizers (Murwira and Kirchmann, 1993).
A complementary use of organic manures and chemical fertilizers has proved to be the best soil fertility management strategy in the tropics (Makinde and Agboola, 2002). Well decomposed farmyard manure contains about 12.9 g kg1 total N, 1.0 g kg1 available P, 4.5 g kg1 exchangeable K, 10.8 g kg1 exchangeable Ca, and 0.7 g kg1 exchangeable Mg. (Makinde and Agboola, 2002).
Organic manure has a greater beneficial residual effect on soils than can be derived from use of either inorganic fertilizer or organic manure applied alone. Combined applications of organic manures and inorganic fertilizers were found best for intercropping sweet potato (Ipomea batatas L. Lam) and corn (Eneji et al., 1997), and for intercropping cassava and soybean (Makinde and Agboola, 2002). Furthermore, nutrient use effciencies have been reported to be increased with complementary applications of organic manures and chemical fertilizers (Murwira and Kirchmann, 1993).
So, organic manures aren't perfect either (36% losses out of the system), and possible a combination of synthetic and organic manures might be optimal (I think they might mean organic and synthetic at the beginning of the third paragraph).
Also, I had a very exciting find today: http://www.sciencealert.com/this-wo...nal-articles-in-an-attempt-to-open-up-science
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Thats because we are not the sort of people who are trying to impress anyone else.