Organic Farmer Network: Network Discussion Summary

Topic: Cover Crops

The excessive rain many of the network participants were experiencing for the first half of this project presented challenges in utilizing covercrops. 

In late April, Cathy says, “The next field I am suppose to be working up has a very weak cover crop, rye/vetch. I read once that if a covercrop is not very lush, thick, etc. you should let it mature to maximize any benefit from it. I have other fields that have fabulous covers of crimson clover, vetch and rye.Which field should I aim for? I figure the CVR fields are two to three weeks from being at their peak (when I would normally put them down). The other weak cover doesn't look like much at all...” 

Ellen replies “I go two different ways when considering your question. Yes, I think you won't get much fertilizer value out of the field with poor growth, but that also means it will work up much quicker and easier than the lush ones - I would think it is also drier at any given moment as well. So, if you can afford to wait for that field to grow and have the time for the lush field to decompose a bit, then that's my vote. If on the other hand you NEED ground now, I'd do in the weak one and give it more presents (compost, summer cover, early crimson in Sept) later!!”

Ken replies that his “Cover crops are mostly pathetic. We had a 6 inch rain in one day last October and after that it never dried enough to work soil again so most cover crop seed was broadcast on top of the ground. Germination was poor and with so much rain all winter, there has been little available N to grow rye. The one good cover I have is a field in Crimson Clover sown before that October big rain. I tilled it last Thursday for tomatoes - it was thick, knee high and just starting to bloom. Will plant them later this week, certainly sooner after tilling the cover than I like, but it has been a spring to just do the best we can.”

Charlie replies “My main winter cover is rye/vetch, and my experience with turning it in is much like Ellen's. It is more beneficial to leave it in until it is nice and lush, but some years I have waited too long, and then it takes a long time for it to decompose enough to plant into. I like to wait two weeks after turning it under before planting. The advantage of turning it under before it is at optimum maturity is that the time needed before planting the next crop is reduced. This year about half of my cover was really lush before I started turning it under last week, and I will be putting some of my later summer crops in those areas. The areas where the cover was not as lush can be planted sooner. I still have two fields in crimson clover, which is just starting to bloom. I will let this bloom completely before I turn it under. I tend to stretch the time before incorporating the clover because I like to feed the bees, and it's just really pretty to see that field of red.”

Ken replies again “Obviously the field with good cover crop is going to get the best result this season, regardless of when either is tilled in. Factors in the decision are which field is dry enough, if wetness is a problem, how soon does either need to be planted, what will be the effect on the rotation of tilling either first, if any. If one can be left longer, all other things being equal, consider this - 2 more weeks growth on the big cover crop yields more net gain for the farm than 2 more week's growth on the puny one. If the puny one is like a lot of mine this year, it ain't gonna be much benefit no matter how long it stays out there. Might as well do it in and let the good one keep growing.

One more thing - I usually find that by this time of year, soil is drying faster in sunny windy weather under a big cover crop, than under little cover, due to the effect of thirsty plants drinking. Last week when I was walking all over the farm with a fork trying to find some place dry enough to till and plant, I looked at the field with my best cover crop, which is a fairly wet natured field. That day it was way too wet. The next afternoon it was dry enough to work and then some. I was shocked how much moisture had been pulled up by the clover. It was sunny, breezy and 80.”

Tim praises cover crops “using cover crops have lessen the total amount of weeds that I have but they do serve as habitat for insects nesting material for birds and if used creatively are very useful for the farmer.”

Mark recognizes the advantages of not having winter cover crops: “I sabotaged an area of cover-cropped beds last December to try an experiment...We had gotten around to planting the wheat/winter pea cover only in mid-November, after having spaded in previous crop residues and tilling in the cover seed lightly with the tiller. The crop was not up yet, and I decided to try mulching over the entire area with enough straw to keep the wheat and peas from coming up (we broadcast pelletized chicken litter over the beds before mulching.) Not much came through the straw during the winter, and what did we were able to easily pull by hand prior to opening holes and planting statice in late April. Talk about CLEAN! We have a bit of sedge poking through in spots, but otherwise it was so easy to plant. It would be much easier for us to spade in fall residues, fertilize, replace drip tape, and remulch for the coming season--than to plant green manures and go through all the retilling, shaping, mulching, etc, during the very busy spring period, dancing around with the weather, wet soils, etc. I know we would lose the value of the incorporated material, but then we're incorporating a tremendous amount of mulch...I'm under no illusion anymore that any technique will work in all circumstances, so we'll just see what happens this season.”