Thanks, Gary, for this annotated list of reasons why millets should be rotated with other crops. A few quick thoughts. First is a question about how different millets fit in this narrative. In particular how pearl millet (and sorghum, if we want to widen the scope to "major millets") would work in these rotations. My understanding is that pearl millet's root systems both go deeper than say proso's, and are a lot denser at the base of the plant (such that they even hold up under cattle hooves over the winter in swath grazing systems). Pearl millet is a huge plant, at least in land races I saw a lot in West Africa - commonly 3 meters / 10 feet high or more. How would this crop compare to proso or other small ("minor") millets like foxtail millet, teff, and Japanese millet (the barnyard millet complex)? Second, is the issue of intercropping as having potentially similar benefits for soil structure and nutrient budgets. Recalling here the traditional pearl millet / cowpea (black-eyed beans) system in West Africa, where the beans would be planted next to the millet stalks, fixing nitrogen in the soil, while climbing the stalks above ground.presumably there were I've seen also mention of intercropping (by rows) proso millet and mung beans in China. Beyond N-fixation, presumably such practices also benefit soil structure. On the article about proso in late Bronze Age Central Europe, I also was interested in the apparent socio-economic transitions corresponding to adoption of proso culture. How does a particular staple crop lead to effects potentially different than one or another different crops? And more particularly, how do millets' coming into and out of dominance relative to other crops in diverse regions relate to other changes in the histories of those places. Many factors - soil health, economics, and physical aspects of producing, processing, storing, transporting, and end use... DO, EL, MI, US NAMA On Mon, Feb 2, 2026 at 1:22 PM Gary Wietgrefe via Collab < collab@lists.millets2023.space> wrote:
Bronze age European millets article was extremely interesting because millet introduction appeared to enhance civilization, likely by adding more nutrients and diversifying soil use. Any agricultural system used year-after-year, century-after-century depletes available nutrients. Benefits from crop rotation had been well understood since ancient Rome when Cato the Elder published De agri cultura - Wikipedia <https://en.wikipedia.org/wiki/De_agri_cultura>.
As a millet agronomist, here are some basic reasons why millets should be rotated with other crops:
*Soil structural changes*:
Millets have a fine root system exploring soil and extracting minerals and moisture trapped where large roots from other crops, like corn, have no access.
After millet is harvested, its fine roots die allowing soil organisms and angleworms to invade those dead roots. Worms and soil bioenvironment to further break down millets small soil clumps into nutrient and moisture havens for the next crop to access through reduced soil compaction.
Millets are shallow rooted which work well in rotation with deep rooted crops like corn and alfalfa and legume crops like soybeans and field peas.
Deep rooted crops access nutrients unavailable to millets. After the deep-rooted crops die, their roots also provide worms and soil’s biodiversity to go deeper into the soil profile for water and nutrients while stalks, stems and leaves converted to soil cover get destroyed through biodegradation at the surface where millet can access those previously untapped nutrients.
Legumes, like deep-rooted alfalfa, and medium rooted soybeans and field peas convert atmospheric nitrogen to leaf and seed protein and deposit more root and seed nitrogen for subsequent crops.
Planting the same crop or two crops (bi-crop monoculture e.g. corn/soybean) creates a system of gradually decreasing grain nutrients because they constantly use the same soil profile while allowing pests to get comfortable in that cycle.
*Soil Compaction*:
Flooded soils are compacted as air is removed from natural soil composition. Crops like rice (100% irrigated in the U.S.), and irrigated corn, especially flood irrigated, cause soil compaction. Machinery tracks over water-logged soils compact the soil even more.
Rather than using mechanical deep tillage to break some of that man-made compaction, millets and legumes should be rotated with rice and irrigated corn to use plant roots to naturally disrupt compaction from previous crops.
*Disrupt pests*:
Weeds are pest and naturally look for environments to grown and produce seed. Corn’s slow-growing seedlings in wide rows allow cool season grasses and broadleaf weeks an opportunity to germinate. Hence, billions-of-dollars-per-year are spent on purchasing, applying and ever-expanding research to find new pre and post emergent herbicides to combat weed pests cycles that can be managed through crop rotation. An example could be cool-season field peas planted and harvested early followed by warm-season millets planted as a second crop rather than just one corn crop. Soybeans could be planted the second year followed by corn in a four-crop/three-year rotation.
Fungi and nematode pests are somewhat crop specific. For example, soybean cyst nematodes attack soybeans and decrease soybean yields. That is why soybeans are never continuously planted year-after-year-after-year. Millets are not susceptible to soybean cyst nematodes—in fact millet disrupt the cyst cycle and decrease soybean cyst populations.
Likewise, fungi causing sudden death syndrome in soybeans (possibly stimulated by soybean cyst nematode) is not a problem in millets.
*Change row spacing*:
Corn performs best in wide rows (usually 30 inch rows) with some hybrids yielding best in 20 or 15 inch rows. Corn farmers that rotate with soybeans almost always use the same planter. Consequently, soybeans get planted at the same row width.
Small-seeded grain millets, like proso and foxtail, perform best in narrow rows (6-10 inch spacing).
Rotating crops with various row spacings and deep and shallow root systems access nutrients and moisture in the full soil profile.
*Crop rotation = Agronomic diversity*:
Rotating crops of different crop species with wide and narrow rows benefit all the categories above:
· more nutrient and micronutrient availability;
· access to more nutrients and moisture in the full soil profile;
· keep a specific pest from overwhelming the intended crop;
· increase soil biodiversity;
· reducing human-caused compaction; and
· decreasing pest pressures (weeds, insects, fungi, nematodes, etc.).
------------------------------ [ . . . ] Date: Sat, 31 Jan 2026 22:41:58 -0500 From: Don Osborn <don@milletsalliance.org> Subject: [Collab] Proso millet improved life in late Bronze Age Europe To: "NAMA's Collab list" <collab@lists.millets2023.space> Message-ID: < CA+RHibWt9bN3xSbAeFVaP5eMbmCmX0KLAOYMNBsGL60_PZokTg@mail.gmail.com> Content-Type: text/plain; charset="UTF-8"
Interesting recent research using new archeological techniques found that introduction of proso millet (aka broomcorn millet) in Central Europe in the Late Bronze Age appeared to have led to more sedentary culture, improved diets, and reduced inequality.
An article about the research: "Millet farming marked a turning point in life during the Bronze Age," bySanjana Gajbhiye, Earth.com, 06-08-2025
https://www.earth.com/news/millet-farming-marked-a-turning-point-in-life-dur...
The research article & its abstract: Cavazzuti, C., Horváth, A., Gémes, A. et al. "Isotope and
archaeobotanical
analysis reveal radical changes in mobility, diet and inequalities around 1500 BCE at the core of Europe." Sci Rep 15, 17494 (2025). https://doi.org/10.1038/s41598-025-01113-z
Abstract: "The transition from the Middle to the Late Bronze Age (around 1500 BCE) in the Carpathian Basin was parallel by drastic cultural changes in Central-Europe, which strongly influenced the dynamic of prehistoric Europe. The cultural fragmentation of the Middle Bronze Age (2000 − 1500 BCE) Carpathian Basin was followed by a more homogeneous development at the beginning of the Late Bronze Age (1500 − 1300 BCE), with the appearance of the Tumulus culture. In the beginning of this period, the long-used tell-settlements were abandoned, furthermore new pottery styles and metal types appeared. Whether these changes were caused by immigration, or a local adaptation to external influxes, has long been a matter of debate. Our study investigates this transition from the point of view of diet and mobility from several key-sites of Hungary. Our results show (1) low migration rates and a shift of migration trajectories; that (2) the beginning of the systematic consumption of Panicum miliaceum was from 1540 − 1480 BCE; that (3) the decrease of average animal protein intake was parallel by an increase of cereal consumption and a tendency to less unequal diet. Overall, our results shed new light on the dynamics of complex change in Bronze Age Europe."
Don Osborn, PhD (East Lansing, MI, US) North American Millets Alliance
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-- Author, Gary W. Wietgrefe, https://www.RelatingtoAncients.com/ Enjoy Wietgrefe's (pronounced "wit' grif") dozen books, patents, and international research on millets, agronomy, cultural changes, travel adventure, poetry, and history.
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