Double Dibbler
Planting Tools
After trying various planting methods, I made a double dibbler with a 2×4 and some sharpened hoe handles. Drill 2 holes the same size as the hoe handles 12 inches apart in a 17 inch 2×4, put the handles through the 2x4 to the desired depth, and drill 2 screws through each side of the 2×4 to secure the handles in place. I was able to make holes 6 inches deep but sometimes this required 2 jumps on the 2x4 with all my weight, sharpening the ends of the dibbles helps. This takes 5-15 seconds or more per 2 holes and is a lot of work.
(Update 2024) Do not use a dibbler if you can avoid it. A 3 ft garden augur is much faster, can go deeper, won't compact the soil as much, and is less work than a dibble! A cordless drill will work but will only make a 100 or so holes at most per regular battery so if possible use long extension cords and a corded drill. The process takes 1-2 seconds per hole, drill step drill step drill step.
Here is a list of planting methods and areas were tested in 2023.
- No-Till, planted early, double dibbled 6" deep, sod scrapped later, hand watered
- Roto-Tilled in 16" wide strips, planted early, double dibbled 6" deep, not watered
- No-Till On Slope (planted twice, double dibbled 6" deep, co-planted with falcata, drip irrigated)
- Tilled On Slope (planted late, double dibbled 6" deep, no competing vegetation, not irrigated)
- Tilled Field 1 (planted early, double dibbled 6" deep, not irrigated)
- Tilled Field 2 (planted late, furrowed 12" deep with middle buster, hand seeded, backfilled using rebar harrow, not irrigated)
Corn No Till
In early May we planted 5 patches with 5 varieties of corn (15-30 seeds each) 300 feet apart in hills using the double dibbler, 4 holes in a square about 8 inches per side directly in the sod. After the corn sprouted and did poorly due to lack of water, we scrapped off the top 1-2 inches of sod to expose bare soil and made a trough to hold water and fertilizer. Even though we planted 4 seeds for each hill we lost some so remade a collection troughs for each surviving plant. This planting method was the poorest of any tried and were eventually watered by hand to try and recover seed to replant the next year.
(Update Aug 19 2023) The hand watered Hopi White and Pink in the middle of Field 2 are yellowing but about half of the Hopi Pink have ears. We have given up entirely on the dibbled Hopi Purple, Concha White, and Pima 60 Day corn as they have been stripped by grasshoppers and will not produce.
(Update Sep 8 2023) The Hopi White produced a few ears and some the kernels were crosspollinated by the blue. The description of Hopi White states that it is suitable for deep planting. Hopi White kernels are white at the crown of the kernel with pink tinges around the edges while the cross pollinated are marbled white, pink, and blue. I have harvested about 6 ears from the 14 Hopi Pink plants with a few green ears remaining among the other plants (some produced 3 ears per plant and percentage wise produced more ears than the white).
No till may be good in many situations but tilling may be the easiest way to clear weeds, kill grasshopper eggs, incorporate fertilizers and organic matter, and condition soil in new plantings. Cultivation methods should be adjusted based on experimental results from trial and error because no one method is suitable for every environment. If an area is going to be maintained for gardening, till minimally and as needed to achieve the desired results. There is a video of Akhima clearing her field with a mattock and not a weed/sagebrush was left standing. Sagebrush are a refuge for quail but do not belong in the garden or corn field and unlike rabbitbrush does not produce nectar for bees. In the corn fields of the southwest desert no weeds are allowed to grow as they compete with corn for water. I have found that Hopi Corn does not like interplanting or competitors including alfalfa, chickpeas, beans, sunflowers, lambsquarters, quinoa, grasses, and other plants/weeds. I have had better results rotating legumes with other crops when compared to the three sister method or interplanting crops. Studies show that living alfalfa only releases 2.3 lbs of nitrogen per acre from decaying roots (the largest contribution on direct N transfer for living legumes) meaning they don't significantly increase soil nitrogen unless tilled into the soil.
Roto-Tilled 16" Strips
We continued planting and used a 16″ wide roto tiller to till 6-8 rows roughly 4 feet apart 20 feet long in areas that looked to have more vegetation and used the double dibbler to plant seeds 6 inches deep. We planted Hopi Turquoise and some other colored varieties for this test and filled out the area in rows with Hopi Blue. We didn’t water with this method and some of the corn has gotten to 30 inches tall. Comparing the roto-tilled patch and tractor tilled field with the same variety of corn separated by 20 feet, the roto-tilled patch is much less vigorous. The picture here is of the best roto-tilled patch, Hopi Turquoise, which is not near the tractor tilled field. I accidentally pre-sprouted the Hopi Turquoise seeds which improved seedling emergence. I didn't think much of it till I read E. Ray Gard's results on pre-sprouting corn seeds.
(Update Aug 18 2023) We have have given up on the two roto-tilled patches due to severe defoliation by grasshoppers.
Tilled Not Irrigated vs No Till Irrigated
Some of our corn seeds failed to dry during the 2022 winter and molded in spring 2023 so I ordered 6 lbs. of Hopi Blue Corn to replenish for 2024 planting and to plant in the drip irrigation area. Accidentally, all 6 pounds got pre-soaked rather than the 600 seeds needed so we stored the soaked seeds in the refrigerator, soaked the moldy seeds, and had an emergency tilling and planting spree in early June.
The tiller had broken down after doing part of the slope right next to where we had the Hopi corn success in 2022 so my wife planted a few rows there. This was done without a dibbler and about 4-6 inches deep with a hoe at the same time I used the dibble in the drip area. This is the same area we had success in 2022 and it is on a slope where underground water may be closer to the surface. It looks dry but the corn is growing quite well, with no weeds. It was initially overplanted but I thinned them to 8-12 inches apart and doing they are notably better than the drip irrigated area next to it.
No Till On Slope (interplanted with falcata and irrigated)
In 2022 we planted falcata which adds nitrogen to the soil and in early spring 2023 we planted korean radishes. Falcata is a yellow flowered alfalfa relative with a fibrous root system which competes well with other grasses and weeds for water. When the radishes were finishing I interplanted with corn but despite irrigation and trimming the falcata the corn didn't grow as well as the tilled weedless unirrigated slope next to it. On first planting I mixed a little fertilizer with loam to backfilled the holes but the corn did not germinate well. I later discovered this seed had very poor germination rate presumably due to mold. I top dressed and replanted again with new seed and backfilled with regular soil. In the picture above a little of this irrigated section is visible behind the non-irrigated green in front, they look pretty pathetic. Next spring I plan to rototill the falcata in the rows but leave it between rows, alfalfa does not belong in the corn field or garden.
Some of the corn had longitudinal stripes of green and white/yellow which would indicate a Zinc or Magnesium deficiency. I had gallon of left over micronutrient solution (including zinc) which I added with Iron and Magnesium to 200 gallons and irrigated corn with this (which may have caused surface fertilizer to integrate). There was some improvement but the area over the septic line did best of all. All indications point to a need to till in extra fertilizer before planting to compensate for the high pH of the well water.
(Update Oct 8 2023) Some of the corn in this patch over the septic line grew much taller and made ears (even some triple ears) indicating a fertilizer absorption problem due to pH, not enough fertilizer, or a combination of both. Tilling in an appropriate amount of fertilizer should fix the problem.
Tractor Tilling & Cultipacking / May 6 2023
In early May, to clear sagebrush and make a place to plant we used a 27hp tractor with 4′ tiller and tilled about 1/3 of an acre and firmed the soil with a cultipacker. We made 2 double dibblers and hand planted with 2 seeds per hole. Initially we used a cross pattern but quickly discovered it was too much arm movement and easier to make 2 parallel sets of holes about 8 inches apart, a 12 x 8 inch rectangle or double row 8 inches apart. We used the dibbler to measure 2 feet between patches and 3 feet between double rows, which is roughly 3' 8" on center but it was all very rough.
While using the cultipacker the tractor's wheels packed the soil and emergence was poor in these areas and using a cultipacker is not advised. The area in the middle that previously had sage brush did better than areas nearby which had short grass. Areas with a slight south slope seem to be better which coincides with where thicker snow builds up in the winter (wind is predominantly from the north). It is now mid July and the corn is clearly heat and water stressed with rolling leaves but some are 6′ tall, tasselling, and a few are making ears.
(Update Aug 18 2023) This week we had a heatwave over 100°F and the grasshoppers have severely damaged the leaves, silks, tassels, and are damaging the corn kernels. Spraying diatomaceous earth did not help, but laying down bands every 4 or 5 rows and around the whole field had some effect. For smaller fields it is a good idea to buy or make wire screen shaped covering to place over the ears allowing pollination while providing protection from both grasshoppers and birds.
There are some ears with blue corn showing at the tips, About 75% the this field is not doing well and only 1/6 or less may produce some corn. The plants are at least 50% yellow or brown due to drought and insufficient of fertilizer. Without some changes in management this planting method does not yield enough to be worth the investment.
Field 1 / Jun 11
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Field 1 / Jul 21
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Field 1 / Late July
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Corn Ears / July 25
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The image above on the right taken in late July shows a Hopi Blue Corn stalk planted in early May and silk emerging from 2 nascent ears. If any of this corn produces there should be a higher percentage of seeds that will germinate and produce corn again under local conditions the next year. The other types of corn which were dibbled and being watered including Hopi White, Hopi Pink, Hopi Purple, Hopi Turquoise, Concha White, and Pima White are producing tassels but all are extremely short, as short as 1 foot including the tassels. Shorter varieties of corn which mature early should also have an advantage and might be able to produce ears using only moisture from spring thaw. If we can grow corn varieties that take only 60 days to produce ears, impacts of drought, heat, and grasshoppers could be minimalized.
(Update Oct 8 2023) Field 1 produced very few ears compared to the area planted producing less than 10lbs on mostly misshapen ears. This is a failure and 50lbs would have been more encouraging. This area still has potential and we will try again next year by tilling in more fertilizer and planting a mix of early maturing corn and sorghum.
Field 2 - (tilled, middle buster furrowed, and rebar harrow dragged)
The tiller was fixed by mid June so we soaked all of the molded corn seeds some of which were still good and combined with accidentally soaked 6 lbs and planted another 1/2 acre. The location was near where we had planted some Hopi White and Hopi Pink with the dibbler. After tilling we used a middle buster to make 12 inch deep rows about 4 feet apart, sprinkled the corn into the furrow, then pulled a woven rebar harrow upside down behind the tractor to fill in the rows with soil. This was much less work than dibbling. For this planting we did not fertilize and the corn was 1 - 1 1/2 feet tall by mid July.
Even though I had already planted Hopi Pink and Hopi white I decided to use this area because it appears to have more underground water and water and water availibility takes priority over keeping the different strains separate. Interestingly corn is one of those plants where the seeds themselves display characteristics from the pollen donor (xenia effect), so the blue kernels can be removed from the white or pink ears to recover the pure strains.
The pictures below are of Field 1 - tilled-dibbled on the left compared to Field 2 tilled-furrowed-dragged on the right.
Field 1 / Planted May / Aug 18
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Field 1 / Diatomaceous Earth / Aug 18
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Field 2 / Planted June / Aug 19
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Field 2 / Poor Coverage & Lodging / Aug 19
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(Update Aug 18 2023) The second tilled-middlebuster patch is still green, taller than the dibbled Hopi White and Hopi Pink right next to it despite being planted 1 month later. No fertilizer was added to this field but there were some cow bones in this area. The two possible explanations are that either the soil is better for historical reasons and/or that there is more underground water in this area. (Update Aug 23 2023) Field 2 is doing quite well and a large percentage of corn making silk.
(Update Oct 09 2023) This field is still green and many stalks have ears which may mature soon enough but most plants are too small or too late to yield viable corn seed. This a partial success. Compared to the first field it is much better and greener though planting late still seems ill advised as much of it will not be mature by the first frost in 2-3 weeks. We already had a layer of ice on the windshield one morning, so presumably there were freezing temperatures in certain areas though the corn and tomatoes are undamaged. This area is the best so far and appears to have enough moisture if the fertilizer problem is fixed. Forecast for the first frost date is Oct 29th which is quite late. Our usual first frost is around Oct 10th.
Field 2 / Still Green with Huge Ear / Sep 25
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Field 2 / SuperFat Stalk / Sep 25
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Field 2 / Kernels on Tassle / Sep 25
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Field 2 / Red Ear / Sep 25
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Dibble & Watered / Hopi White Corn / Oct 8
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Hopi Pink Corn Oct 11 - Unusual Morphology
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(Update Sep 17 2023) We have had intermittent rain and the first hard frost date has been pushed back from Sep 29th to Nov 9th, so it looks though the corn that was pollinated this last month will have a chance to mature. I removed an ear that was laying on the ground, had yellow husk, and had some bird damage. Peeling back the husk exposed shiny blue kernels almost ready to harvest. The seeds should be viable but I'd prefer to wait as long as possible and harvest Nov 7-8.
SuperFat Triple Ear
Several plants exhibit a distinct phenotype where the plants were greener, have wider leaves, wider stalks 2x cross section area, much more robust looking prop roots, and triple ears with silk emerging from the tip and from between the layers of husk on each side). This robust growth is probably not due to genetics. Multiple ears on the same shank is reported to be more common when high density corn is planted farther apart and when conditions for growth are optimal. Bouquet corn is an extreme variant of this and can result in reduced or no yield (silk from side ears emerges later and are not pollinated). Triple ears can be detrimental to production since plants waste energy on the side ears and the silk of side ears emerges too late to be pollinated. Plant spacing should be adjusted to optimize production (which may also help canopy cover and reduce soil evaporation).
Discussion
For both Field 1 and Field 2 there are areas that have done much better than the rest. About 60% of Field 1 the corn plants failed to mature (less than 3.5ft tall and of the rest only 1 in 5 produced ears. Some areas in Field 2 did not get planted and in other areas corn was planted too close and not thinned contributing to poor growth. Since all were planted similarly variable results must be due to variations in soil fertility or availability of underground water. For future experiments fertilizer will be applied at rates similar to commercial farms to eliminate the soil fertility variable to focus on planting times, planting areas, planting methods, and strain characteristics.
Corn was dried on the cob at 72°F on the floor of winter plant room which was fairly bumid and shelled February 2024. Three batches were tested for germination named dark, light and very light where the very light was a paler blue but without a dent and all 3 batches germinated reasonably well with the lowest being 75% for the very light and these were mostly very small or malformed kernels. In all germination results most kernels that did not germinate appeared to be small malformed kernels which could be removed by screening. I later shelled 3.5lbs of "very light" which were slightly dented but discarded cobs which were even lighter blue and significantly dented. As a note Field 1 was not half an acre but closer to 1/4 acre and the portion of Field 2 that was planted is about the same so aprox, 1/2 an acre total. About 150lbs of corn in Field 2 was not mature enough for seed but would be suitable for human or livestock consumption, milk stage or post milk stage. A total of 57lbs of shelled corn for planting was harvested. This is 1-2% of expected dry land corn yield and with proper fertilization yield in 2024 should be significantly higher.
Seed Harvest, Drying, Storage, & Mold
Corn should be allowed to mature and dry in the field until the husks are papery and brown. It is recommended that corn be harvested before the first frost but corn can continue to mature after a frost as low as 28°F for a few hours if the stalk and shank of the corn is not frozen and killed. Upper leaves may be frozen but the stalk will continue translocation of sugars to the kernels. Corn is mature once kernels have developed a black later separating the kernel from the cob.
Corn can be hung to dry for several weeks before storing but in cool or humid conditions air drying may not be sufficient and improperly dried corn will mold in storage. In Spring 2023 I found much of the corn I had saved for seeds in partially open mason jars were stuck together with mold and germination for this batch was poor, about 10-50%. Corn seed can be dried in a dehydrator to the recommended 11-12% moisture at the "maximum safe temperature (less than 110°F)" Matthes et. al. (2021), Drying, Processing and Storage of Corn Seed in Tropical and Sub-Tropical Regions, Seed Technology Papers. This paper also recommends that if corn is harvested with a high percentage of moisture, 25-35%, it should be dried on the ear.
Planting Time
Plant as early as weather permits to make use of spring moisture before it dissipates and results could be improved by growing faster maturing shorter stature corn, eg. possibly Hopi Pink, Concha White, or Pima 60 day types like Smoik Hu:n and Ki:kam Hu:n.
Clearing & Plot Selection
Some of these results were dependent on differences in seed quality, strain traits, or differences in planting areas. Depth of topsoil should considered when selecting a site since this can't changed without costly addition of topsoil from outside sources. Select areas with thicker taller grass & forbes which indicate greater water holding capacity and will yield better results than areas poorly covered with vegetation. Low areas do not necessarily better and native vegetation is the best indicator of good planting locations.
Initial clearing of all vegetation is important and it is ill-advised to co-plant corn with other plants because the other plants will compete with corn for water. Hopi corn prefers to be planted further apart than regular field corn since even in irrigated plots spacing seems more important than water. If spaced far apart individual Hopi corn plants can have 5 or 6 stalks each producing an ear if given a long enough growing season.
Tilled Drag Filled Not Irrigated Left vs No Till Hand Watered Right
The picture to the right shows younger green unwatered Field 2 plants next to and almost the same size as yellow watered dibbled plants. The greener plants in the picture are using ground water from winter snowmelt which would have a more neutral pH compared in comparision to the well water. It is highly likely that the well water which is pH 8.2 is limiting the update nutrients especially iron and zinc. Also the slope nonirrigated corn is greener and taller than the slope drip irrigation corn which supports this hypothesis. With this soil and fertilizer regimen no water is better than high pH 8.2 well water. Doing some research on these two crops, corn is more likely to respond to application of zinc than sorghum and less likely to suffer yield loss due to iron chlorosis than sorghum. Some of the corn including unirrigated corn has white/yellow longitudinal bands which an indicator of zinc deficiency. It is worth doing a test to see if adding a supplement fertilizer of these two micronutrients will improve the foliage color and rate of growth.
Late results for the drip irrigated showed that the corn over the septic did much better than the rest, so water quality issues can be remedied by more fertilizer or possibly the septic water does not have a high pH.
Field 1 / Jun 11
When the corn was 4 inches high we added Organic Garden-Tone, just a pinch 1/8tsp or less, 2 inches around each plant for all planting styles except Field 2. I am not promoting this fertilizer but it is organic, readily available, and reasonably priced. We also tried adding this fertilizer mixed with loam during planting to the hole in the drip irrigated area which resulted in very poor germination and the area. We replanted this area again but without fertilizer. You can see the corn in Field 1 below clearly need fertilizer but adding fertilizer now in the heat of summer without irrigation would either kill the corn or just sit on top of the soil and blow away.
As of August 4th the corn has yellowed and turned brown on the lower 1/3 of the plants, even the ones that are doing the best. Since these are not irrigated it is not just a problem with well water pH. Top dressing at the 3-4" height does not work as there is not enough rain after June 10th to incorporate the fertilizer into the soil and so the fertilizer must be tilled in before planting.
I found out the local fertilizer company will loan me a spreader if I buy from them. I bought some zinc and read that 30lbs per acre will "cure any Zinc deficiency for many years". I also bought some FeSO4. Fertilizer rates are per acre and usually not expressed as actual available forms and more confusingly even the unavailable forms are expressed as a formula. Normally when computing ppm for hydroponics simply divide the formula by the listed percent of the ingredient(s). For example for nitrogen below divide target N per acre by 0.46, the percent of Nitrogen in Urea. Sulfates should lower the soil pH and KCl should be used instead of K2SO4 as K2SO4 is very expensive (lesson learned when calculating initial fertilizer rates for winter wheat).
| 220 lbs Urea 46-0-0 | N 101 lbs/acre (120-150 total N) |
| 173 lbs 1152 11-52-0 | N 19 lbs/acre + P205 90 lbs/acre (up to 150lbs) |
| 200 lbs KCl MOP 0-0-60 | K2O 120lbs/acre (up to 150lbs) |
| 52 lbs FeSO4 31% Iron Monohydrate | Iron 16 lbs/acre |
| 30 lbs Zinc Sulfate 35% Zinc | Zinc 10 lbs/acre |
| 44 lbs MgO 45% Magnesium Oxide | Magnesium 20 lbs/acre (*50-100) |
| 18 lbs MnSO4 28% | Manganese 5 lbs/acre |
Dryland Corn Recommendations 120-80-80
For N the following resource Comparison of Nitrogen Use Efficiency Indices for Corn Fertilized with Commercial Urea & Poultry Litter - Alabama Cooperative Extension System is useful. Phosphate recommendations are 60-165lbs per acre. Potash recommendations are 100-200lbs per acre. * Mangnesium should be 50-100lbs per acre and is less than recommended because Magnesium absorption is higher at high pH and the local fertilizer rep. says local soil Mg is sufficient.
Field 1 / Corn Spacing / Jul 21
Another observation is that Hopi Blue Corn plants separated each other by several feet are doing better than those close together. We planted 4 holes in a 8 x 12 inch rectangle with 2 kernels per hole but in places where germination was poor and only 1 sprouted per hill they are doing better. Hopi plant 3 or more paces between hills easily 12 feet apart in some cases. I spaced out the plants in each hill to get more moisture but recently did a rough re-calculation. If each hill is 9-12 feet apart that is 144 sq. feet per hill and with 6-8 plants per hill that is roughly 10-24 sq. feet per plant. If corn roots extend 2' from the plant on all sides which seems reasonable then each corn plant has access to 16 sq. feet of water (counting as a square not with pi). Plants separated from neighbors by 3-4 feet do better than those more closely planted with more neighbors. It is clearly possible that native farmers are on to something and planting with 16 sq. feet per plant results in more efficient ground water use. Planting in a clump will also provide support, reduce wind damage and transpiration, and provide some shade to keep plants cooler in the heat of the day. If planting row style, spacing corn 14-18" apart in rows with rows 2.5-4 feet apart seems reasonable. To optimize fertilizer utilization using broadcast fertilizer application the closer 2.5' row spacing is recommended. Late observation of field 2 suggests plant spacing may be less important, and that location and fertilizer are more important.
As I have little organic matter I'd like to try adding plastic mulch (possibly biodegradable) in between the rows of corn after emergence. A research paper Li et. al (2014), Effect of plastic sheet mulch, wheat straw mulch, and maize growth on water loss by evaporation in dryland areas of China, Agricultural Water Management shows that plastic mulch with crop cover can effectively reduce water loss due to evaporation during hot dry months. Other research suggests it might be possible to get more water infiltration by deep plowing and contour plowing.
A better mulch option may be to plant rye mixed with hairy vetch. Beside the lupine I have noticed a small patch of blue/purple flowered plant on the northeast wet corner of the property and now realize this a type of vetch. Vetch is a nitrogen producing vining plant and is usually planted with a grass like rye so it can climb up the grass stalks. It is easily killed by disturbance and normally killed by mowing or tilling to provide mulch and soil protection before planting corn. The vetch mulch has the added benefit of reducing soil evaportation. I plowed 4 acres on the north of the property in September which would have been perfect time to plant hairy vetch. Something I will try Fall 2024.
Studies with mulch and canopy closure indicate that both together reduce soil evaporation suggesting that closer planting may actually be better. Research on dryland corn production in Alberta Canada where annual rainfall average is 15 inches found that corn grown in 20" row with 30,000 seeds per acre had the highest yeild See Video Here. This may be because higher seeding rates hastens canopy closure and reduces soil evaporation. This would mean 20" rows with seeds spaced 10.5" apart, an idea to test next year.
Afternoon Drought Stress / Jul 19
This year we have 3-5 times more grasshoppers than usual, which are eating the corn leaves, tassels, and silks. Damage is worst around the edge where they come into the cultivated area from surrounding brush and grass. As of Aug 4 2023 the grasshopper situation has become severe and the tops of all the forming cobs have been chewed off.
One suggestion I saw was to dust with flour to gum up the grasshoppers digestive system but using a processed food product to produce unprocessed food doesn't make sense to me. Besides it would be difficult to apply to a large field of corn. Food Grade Diatomaceous Earth is organically approved and works by mechanically damaging the insects exo and endoskeleton without harming plants, birds, or mammals. We tried spraying a solution of DE on plants but this had little effect on grasshopper populations and did not control the damage.
Spraying DE has very little effect on grasshoppers. We then applied DE dust around the field in a 5' band around the field and in between every 5 rows, and this had some effect.
Tilling will also reduce viable grasshopper eggs and planting faster maturing corn varieties which produce ears before grasshoppers populations increase should also help.
In the picture 3rd from the left below mice have eaten the silk and 1 inch into the corn kernels. Grasshoppers eat the silk and leave a small hole at the top of the cob eating some kernel material and allowing aphids into the ears but larger holes through several layers of husks are most likely caused by rodents. The picture on the far right below shows a cob low down on the stalk that has a hole half way down and what looks like a nest or droppings inside. We put 16 mouse traps with peanut butter around the field and 2 at the base of the stalk in the picture and there was a mouse in the trap the next morning. Traps were effective at reducing corn damage due to field mice and were not a big expense or much work.
In early October Field 2 had damage on the top of the ears and upon inspection there were bird droppings on the leaves of some of the corn with the damage. Birds will shred the husks and eat down the cob though the shredded husks. Covering the tops of the cobs with a wire screen tube or cone will allow pollination and protect the ears from both birds and grasshoppers and is probably the best solution. By the time I noticed the bird damage I see very few birds and most seem to have already migrated for winter.
Pest Damage / Aug 18 2023
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Exposed Kernels / Aug 18 2023
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Rodent Damage / Aug 18 2023
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Rodent Damage / Aug 19 2023
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Mature Plant Size
Mature plant size is a variable that should be considered when and testing the ability of corn varieties to produce without irrigation. Shorter plants may also have a less extensive root system and be less drought tolerant. I have 2 types of sorghum the larger of which, Ba YE Qi produced very well in 2022. Despite being more drought tolerant than corn, sorghum does not tolerate deep planting and most reports say sorghum has a shallower root system than corn. I thought sorghum would need some irrigation and did not plant any in 2023 (One stalk grew in Field 2 but did not produce kernels). Some reports state that corn roots can reach 6 feet deep, another that roots of both sorghum and corn roots can extend to 10 feet, and another that sorghum roots can reach close to 8' deep Assefa et. al. (2010), Grain Sorghum Water Requirement and Responses to Drought Stress: A Review, Crop Management. The research article George-Jaeggli et. al. (2011), Decrease in sorghum grain yield due to the dw3 dwarfing gene is caused by reduction in shoot biomass, Field Crops Research shows that stem mass serves as a biomass reserve, and that larger plants with more stem mass were more drought tolerant and continued grain fill better under adverse conditions compared to 3 x dwarf varieties shorter than 4 feet. Not what I expected but interesting. By extension, shorter Hopi Pink may produce sooner but not as well as taller Hopi Blue Corn. Hopi Blue Corn is 5-7 feet tall at maturity while Hopi Pink is 3 - 4 feet at maturity.
Lodging & Planting Depth & Planting Style
Articles online claim that in the southwest corn is "planted deep enough to find moisture in the dry climate" and while moisture is essential for germination, I see no post emergence effect on corn plant at 6" deep vs 2" deep under my conditions. It could be in my location ground water is close enough to the surface or 4" is not enough difference to produce a noticeable effect. Another likely explanation is that in the southwest the essential key is to get sufficient moisture initially to induce germination and spring moisture at my location is sufficient for germination at all depths. At later growth stages planting depth may have little effect on water accessibility and uptake. We have had a cooler summer compared to last year where it got to 117°F. We had 0.003" of rain on Aug 21st 2023, just enough to settle the dust. On hot days over 95°F Field 1 suffered from lack of water and this will certainly impact yield, but temperatures have gone down and it is making ears. The tops are not wilted and light green while the bottoms are brown, indicating to me that when it is cooler a lack of nutrients is more of an issue than lack of water.
Add fertilizer during tilling before planting and plant deeply to reducing lodging. Make a deep trough and use a precision row seeder or hand plant with a garden augur at the bottom of the trough to get even coverage. Pre-sprouting corn will probably improve seedling emergence for hand planted corn as explained by E. Ray Gard.
While a higher percentage of plants in the furrow-drag-filled field are growing well and green, some are lodging compared to other planting methods of which none have fallen over. Spreading seeds by hand in the middle busted furrow and covering by dragging once doesn't give even coverage or get the seeds deep enough. It would be better to use a precision row seeder set to deepest depth, plant at the bottom of the furrow, and then drag across the furrow twice with a rebar harrow turned spikes up.
Planting shallow and in loose soil improved emergence. Plants that were not covered well, were not compacted, or were not planted as deep germinated and grew better, including a few where holes were not refilled properly or completely missed in the dibbled field. Dibbling compresses soil down and to the sides while a garden augur removes soil making it loose for convenient backfilling. It is probably better to use a garden augur to drill to the desired depth 4-10 inches deep at the bottom of the furrow, plant, and then backfill with the loose soil. Compared to the previous method, the plants will be planted lower in the ground, experience less air movement, and hence have access to to more water and loose less water to transpiration at the bottom of the furrow. More work than the previous idea but worth a test.
Genetic Selection & Promising Varieties
One conclusion is that some Hopi Corn seeds can emerge when planted deeply but a portion will not reach the surface and deep planting slows initial development. It may be possible to increase the percentage of successful emergence from depth by maintaining selective pressure for this trait.
I don't have a large set of data to recommend any varieties but both Hopi White and Hopi Pink grow about the same while Hopi Blue is larger and takes longer to mature. Some of the Hopi Blue from Field 2 were still putting out fresh silk on Oct 20th. It is likely lack of fertilizer and irrigation delayed maturation of Hopi Blue in Field 2. Also, it is difficult to make a comparison since the Hopi White and Hopi Pink were watered and most of the Hopi Blue was not irrigated.
Things Learned & New Questions
- Store seeds properly to prevent moulding.
- Choose best planting areas based on native vegetation.
- Larger plants may be more drought tolerant?
- Plant earlier to make use of spring moisture? (newest results - later planted Field 2 is doing better hmmm).
- Plant or select better varieties that get bigger faster and produce earlier.
- Correct soil deficiencies to improve plant health and hasten maturation.
- Clear all vegetation and till in fertilizer before planting.
- Tilling helps to reduce grasshoppers populations.
- Planting depth may not affect water availabilty under my conditions.
- Plant at optimal distance for even coverage, light utilization, and ground water usage.
- Improve planting style to improve emergence, reduce transpiration, and minimize lodging.
- Pre-sprouting seeds may improve emergence if planting by hand.
- Monitor pest problems and plan corrective measures.
- Leave spent canes standing or lay down to catch winter snow.
- Use previous years crop residue as mulch the next year, don't till in.
Future Experiments
As soon as I get time, I am going to test percent germination and emergence when planted deeply of several varieties to get an idea of how these seed types and lots will perform next year in the field.
I'd like to try contour plowing to increase water infiltration and add plastic mulch between rows of corn after emergence to reduce soil evaporation.
I have 2 different varieties of heirloom nitrogen fixing corn which I will try to cross to a short early producing variety. These nitrogen fixing corn seeds are costly and the plants require a long growing season and get very tall. I plan to germinate indoors and then transplant to a wind protected area, use pH'd water, and use supports to prevent lodging. Later plant the desired short variety below and if they are out to sync save pollen from one variety to pollinate the other. I have no idea if nitrogen fixation would work in a dry environment. There is likely a physical limitation as these types of corn exude a gel on aerial roots to provide a moist anaerobic environment for Nitrogen fixing bacteria. On the other hand it could be possible that with selection the gel could be produced on prop roots a few inches below the soil and provide some level of nitrogen fixation.
In 2022 we had a good harvest of sorghum with only 4 25' rows and it would be worth it try various planting and irrigation methods as sorghum has lower nutrient requirements than corn, is more drought tolerant than corn, and roots grow almost as deep as corn. In arid regions of Africa some crops are planted at the bottom of a hole dug a couple feet in the ground and it would interesting to try creating swales to collect water and plant corn & sorghum.
Summary (Nov 17 2023)
There are many more variables to successfully growing corn in dryland conditions than I previously thought. Plants need to get to sufficient size quickly enough to get access to deeper moisture before surface moisture dissipates and the best way to achieve this is to plant in areas with sufficient accessible ground moisture and adding appropriate amounts of fertilizer. All 2023 experiments did not have adequate fertilizer. Planting date should be as early as possible to make use of spring moisture and to avoid corn freezing before seed maturity. Field 2 yielded about 100 ears usable for seed with another 100 suitable for consumption and with many more too late and not fertilized. Planting style with fertilizer correction should be closer together to minimize triple ear and hasten canopy closure which will shade the soil and reduce evaporation. Consider using a mulch, plastic mulch if nothing else is available. Drill holes or plant with a row seeder at the bottom of a trough to get even coverage and reduce lodging. Location is important and Field 1 has less moisture than Field 2. Use faster maturing varieties if possible, test Hopi White vs Hopi Pink vs Hopi Blue vs Greasy Head vs Pima 60 day.