We’ve entered our first heat wave in Maine, and the spinach has done what spinach does in the heat– hurry to reproduce. Before it bolted, I was able to get two successive harvests of pretty nice looking spinach (if I do say so myself) from our experimental plots. When setting out this experiment last August, we had a few questions, but the simplest one was: is this even going to work in the frigid north? A couple of weeks ago I reported that things were looking pretty good, and now I have some data to share along with more photos.
Late summer planning and planting
Because this system requires some forethought and action (but don’t be dissuaded!), here’s an explanation of what we did last year. Do you have your first round of crops coming out of the ground soon? Might be time to think about where you could put forage radish into your fields in August in preparation for next spring’s crops.
Before cover crop seeding in August, the plots were tilled. Unfortunately, this is not a permanent no-till system, and in order to provide weed control in this organic system, tillage before cover crop seeding is necessary. The forage radish plots were given 40 lb N/acre at seeding to give them the boost needed to grow deep roots and capture even more N from deep in the soil profile. This, and all of the fertilizer used in this trial, was in the form of mustard seed meal, fish meal, and soybean meal (mixed).
We seeded forage radish on three different dates starting on August 4. We got lucky because the Google satellite happened to take an aerial of the plots growing on Sept. 17. The final forage radish planting (Sept. 1) is visibly much smaller than the first two, and you can see the weeds growing in the control (no cover crop/weeds) plots.
The reason for the three forage radish seeding dates was to try to determine the required seeding date for good weed suppression in spring. The most important message here is that September 1 is too late to get good weed suppression by forage radish in New England. Those growing degree days in August and early September are essential to get the radish to grow and establish a closed canopy early enough to inhibit weed seed germination.
I thought that it would be swell to have an experimental design that had cover crop planting in one direction and spring vegetable planting in the other. This created wheel tracks in fall that I think affected both emergence and plant growth in spring (see photo with carrots). Soil compaction is no joke, and even though forage radish alleviates soil compaction, it cannot do so in every inch of the field. Because we tilled the soil prior to cover crop seeding, it wall all the more susceptible to soil compaction when we seeded. Too many details? But it’s the details that matter!
Winterkill in New England, unlike the mid-Atlantic, is pretty much guaranteed as we generally get successive nights in the teens (F) in November or December. Bigger radishes die with less severe temperatures, so the latest seeding date stayed green a little longer. All were dead by January.
As soon as the ground thawed in mid April, we seeded spinach, carrots, and peas using a MaterMacc seeder. Using a precision seeder is not necessary (see post from last week about seeders), but they work very well under a variety of conditions.
In addition to the cover crop treatments, we looked at tilled vs. no-till seeding and two fertilizer rates (organic fertilizers). This is a very sandy, low fertility soil. As mentioned above, at the time of cover crop seeding in fall, forage radish plots were given 40 lb N. It would not be a normal practice to apply 40 lb N to a fallow field, so this 40 lb N was applied to the no cover plots in spring, in addition to the fertilizer treatments. For the fertilizer treatments, the 100 lb N treatment received 50 lb N at seeding time and 50 lb N in late May. The 50 lb N treatment did not receive fertilizer until late May when all of the plots were looking N deficient.
Organic fertilizers like fish meal and soybean meal take some time to mineralize, so 50 lb of N in organic fertilizer is not like adding 50 lb of N as ammonium nitrate. It is likely that much of that N has still not mineralized.
All plots were hoed using a stirrup hoe in late May.
Well, two blocks had major cutworm, wireworm, and disease problems. Ugh. Neither the tilled nor the no-till spinach came up in any quantity that a farmer would keep in the field, weed and manage through to harvest. I put on my farmer cap and made that judgment, though I did keep them weeded so I can get soil nutrient data. The yield results of the other two blocks follow. Two is not enough to draw any sweeping conclusions, but these results provide some fodder for discussion and certainly they answer the question of whether this forage radish no-till vegetable system is possible in New England. Yes!
It appears that all three forage radish plantings increased the spinach yield. The way I interpret this is that the 40 lb of N applied to the cover crops in fall brought more value than 40 lb of N applied as fertilizer to the no cover plots in spring. This could be in part because the forage radish tissue actually decomposes faster than organic fertilizers, providing the needed N boost at the right time for spinach. This is speculation- we would need soil samples and a variety of other data to show that this is indeed what is happening.
The no-till forage radish plots tended to have lower plant density, which may have affected yields, but I don’t think this is a flaw of the system- I think it was the mistake of the operator (me…) with that whole wheel track thing. A future year will tell.
But the no-till yields weren’t bad! A few days before the first harvest, this is what the plots looked like:
I could probably bore everyone to sleep with my thoughts on what is going on here, but I will stop with that. I’d welcome any comments or questions people have in the comments section or send me an email.
Next week, I’m excited to share results of no-till carrots! As a preview, here are some photos:
Oh, and we’ve got peas by the 4th of July from our no-till seeded peas: