nitrates and northern composters
mpludwig at students.wisc.edu
Thu Jan 30 23:04:05 EST 1997
At 06:25 PM 1/30/97 EST, you wrote:
>Nitrates/nitrites and nutrient ions in fertility cycles...
Excellent post Jack, much fun to read. I'll add a few comments as we go...
>A couple facts combine in this process which are of interest to the soil
>fertility cycle as it concerns nitrogen:
>1) plants roots need to be PRESENT AT THE PLACE AND TIME WHEN BACTERIA DIE if
>they are to absorb the nitrogen before it is transferred to other uses or
>2) much nitrogen is lost to gassing leaching, or washing away if it is not
>quickly absorbed by other micro-organisms or plants.
>What the preceding paragraph means is that the greatest efficiency of nutrient
>use/uptake per pound of nitrogen applied or fixed by legumes is obtained when
>the breakdown of the fertility materials or nitrogen-fixing nodules by
>and the deaths of the consuming bacteria, occur IN THE ACTUAL ROOT ZONE OF THE
>GROWING PLANTS. For this reason, much greater use of the nitrogen content of
>fertility materials is made if they are applied as mulches as opposed to
Interesting stuff, N utilization in pastures is just such a model, which is
why pasture is the best form of "traditional" farming we have. In pasture
the N often come directly from legume noduals (and other root materials)
which sluff off after a grazing event. This provides a burst of N for
grass growth. For maximum N utilization plant a grass legumen mix with at
least 40% legumes. If we consider manure pats as a mulch (especially when
dispursed by chickens/chooks, worms or insects) this system gets even better.
>Further advantages of mulches over composts include:
>1) soil cooling in hot environments (15 degrees F cooler at 6 depth than
>unmulched soil as measured by myself in May in Texas);
Turn this one on it's head northern dwellers. Don't mulch in the spring
when you need to warm up soils; consider sheet composting (adding redily
decomposable materials to the soil and composting in situ to add heat
through biological activity.
>2) narrowing of daily soil temperature swings, eg, cooler in daytime and warmer
>3) importantly, earthworms are much happier under a mulch than under just
>compost, for many of these reasons listed here, and also because they eat
>soil-surface detritus and so will be found most numerous under a
Earthworms, like all soil life are happiest when fed. If the mulch is a
good worm food it will make them happy, thogh some species would like it
incorperated a bit more than others.
>4) improved soil moisture retention through lowered evaporation (as well as
>lower plant evapotranspiration due to lowered temperatures;
Again, up north we may fight to drain/evaporate the water and may find nice
black compost a better bet than mulch early in the season. Cover crops
also help dry down soils. (I know, I'm not planting in the right places,
but sometimes there's not much selection).
>5) less soil compaction from impacting rain, less splashing by rains (dont you
>just hate washing savoyed greens covered with dirt?), and;
>6) ultimately, less work is performed if fertility materials are just
>sheet-composted and left to do their own work.
Pig turned compost, easy for you, fun for the pig....
>Sodium also causes clay soils to collapse and become dense, slippery and
>impervious (salt, up to 4 pounds per square foot of pond surface area, is used
>to seal leaky ponds in clayey areas because of this ability to collapse, or
>deflocculate, clay soils). A side effect of the addition of calcium to
>counteract the loss of a soils available CAC to excess sodium ions is the
>apparently-magical fluffing of the previously-sodium-laden clay soil -- with
>greatly increased tilth resulting. This effect can be dramatic, turning sticky
>clay into dirt overnight. Quite gratifying.
While I love my Ca too Jack, I'm not sure you can expect that fast a change
in salt dammaged soils. Most of the stuff I've seen deals with Gypsum
(calcium sulfate, the main material in most dry wall sheeting for you
dumpster divers) and recomends about 6 months for the full effects to be
seen. In less dammaged soils it will be faster of course. Clays can be
especially tough to work with as when "colapsed" the infiltration rates
stink and it's hard to get fertilizers into it. One of my tricks? Mix in
compost! Adds a little instant fluff and crumb structure through the
formation of clay/organic complexes, and also reinoculates train wreck soils
to get back a decay cycle. Gypsum is a nice sourse for higher pH soils as
it should not move pH much. The fineness of your calcium will also effect
the speed at which it disolves in soils.
>Moral of the story: use rock powders (but go lightly), check calcium
>available -- which means watch pH also), and place fertility materials right on
>the ground, in the garden, to decompose. Brush your teeth, wear clean
Marks moral, to each thing it's place, compost where it fits best and mulch
after summer gets rolling here in the Northlands.
Two other tips:
P bearing rock dust will help tie up excess N in your compost, retaining it
Consider adding clays directly to the compost pile for the same reason.
This is especially valuabe if you later move the material to excessively
sandy areas; CAC (CEC?) is a factor of the clay and organic fraction in the
soil, and a little clay will go a long way in the sand, especially if
complexed with OM ahead of time.
The old farmers say "Clay into sand is money in hand; sand into clay is
money thrown away."
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