The Cerén farmers tolerated and possibly even encouraged the growth of wild and weedy species within their maize fields. All of the weedy species recovered from these fields have known uses nutritionally, medicinally, or for other purposes where they were incorporated into ceremonial activities or valued as a decoration . Amaranthus, Crotalaria, and Portulaca are all significant contributors towards Mesoamerican diets today and are often intentionally integrated into milpa agroecosystems . Kekchi villagers in Belize only remove weeds if a particularly dangerous variety has encroached, such as those with thorns or spines . The Kekchi Maya do not view weeds as a threat to their crops and consider their constant removal to be futile. Weeds can be useful additions whether fertilizing the soil, increasing moisture, or serving as a foodstuff. In fact, milpa agricultural systems in Mesoamerica commonly incorporate weedy species that are considered nutritious and edible, what is called quelites . Ethnobotanical records show that the majority of species procured for medicinal purposes are collected from disturbed habitats, such as agricultural fields, where weeds are predominant . Nine of the wild and weedy species within the Cerén fields have known medicinal applications to present day Mesoamerican groups . Amaranth was the second most ubiquitous herb within the fields, hydroponic rack occurring in all operations excavated except for Op. AN, and is an important edible green and grain throughout Mesoamerica .
The overwhelming amount of Spilanthes acmella achenes recovered could have been used as an herb or spice to flavor daily meals. The S. acmella achenes were so abundant that their distribution within agricultural contexts can reveal how the herb is significantly more prevalent within the fields closest to the households , suggesting that the farmers encouraged its growth. This follows Killion’s assessment that mono-cropped agricultural fields may have been farther from domestic structures, whereas multicropped or polyculture fields would have been located closer to where people lived. Alternatively, farmers may be more tolerant of weeds during the final stage of a cultivation cycle, as the maize crop is ready to be harvested . Many of the maize stalks recovered here via plaster casts were bent over so that they can dry within the fields , as if the agriculturalists were just about to collect that season’s harvest. The bent stalks prevent moisture from entering the fruits since water can no longer be taken up through the stem and rain can no longer enter the cobs as easily either. The apparent abundance of wild and weedy species within Cerén’s milpas provides further evidence that these fields were at the end of their growing season and perhaps the weedy herbs were simply not an issue that required manual removal. Many milpa agroecosystems burn the entire field in order to prepare the landscape for the next planting cycle, thus managing any weed populations that had become overgrown. Relatedly, it has been documented that the Lakandon Maya take ashes from piles of collected weeds and leftover crop residue and spread them throughout their fields to provide organic matter as a fertilizer . Since the soil samples collected for flotation in this study were taken from the interior of the agricultural ridges, it is unlikely that these herbs were only present from burned organic matter spread throughout the area.
If this was the case, the distribution of the weedy species would be more irregular, rather than the pattern of weedy seeds being more prevalent in fields closer to the village structures . It is more probable that their existence in the flotation samples is due to their growth within the fields. These weeds’ strong presence in the fields suggests that they could have held a positive relationship with the villagers and were part of a complex agricultural system; at the very least the weedy species were tolerated within the fields. Recent excavations at the site encountered a roadway feature, a sacbe, leading south out of the village, likely beginning near the village plaza . ‘Sacbe’ is the Maya term for a white road; sacbeob were typically constructed using a white material such as plaster. In the case of Cerén, the causeway was covered with a layer of Tierra Blanca Joven, a white volcanic ash derived from Ilopango, and was about 2 m in width and elevated an average of 20 cm above the ground surface . The earthen sacbe found traveling through the maize agricultural fields could be interpreted as a boundary marker between agricultural plots. During the 2013 excavations, more than one maize field was often present within each operation, separated by the causeway . When the paleoethnobotanical remains recovered from the agricultural fields on either side of the causeway are compared, management practices differ between the western and eastern milpas. The western fields reveal a larger percentage of weedy species per sample than the eastern fields . Yet, the eastern fields exhibit a more diverse assemblage of weedy species compared to the western fields. This distinction could indicate varying levels of attention to weed removal in terms of time and intensity. This variation suggests that different individuals or households practiced varying agricultural management strategies, perhaps even distinct timings for planting, and that the earthen sacbe served as a boundary marker within the fields.
Perhaps the varying presence of weedy species between the eastern and western fields is also indicative of varying perceptions of what a “weed” is to the different farmers tending these fields. Since the western fields exhibits a more limited set of weedy species, the agriculturalists tending this space may have had a more limited set of weedy species that they considered to be of value. The weedy species in the western fields are more limited to those that would have been used as nutritional herbs and foodstuffs, whereas the eastern fields’ more diverse weed assemblage includes more species that have known medicinal applications. Sheets and Dixon characterize this milpa area as the intermediate agricultural zone at Cerén, which exhibits irregular fallowed areas and a great variability in cultivation strategies. Each household likely devoted varying amounts of time toward gardening and management of their fields, with weed removal taking place secondary to other tasks, if at all. The distribution of the most abundant herbaceous species in the assemblage, S. acmella , across the maize agricultural fields reveals a lower abundance of these achenes within the fields closer to the village center. Around roughly 40 m south of the village plaza , the maize agricultural fields begin to exhibit significantly lower counts of herbaceous species within the flotation samples. The species is still quite prevalent in this area, but only amounts to at most half of the quantity of achenes recovered from field contexts closest to the main village. This stark contrast could be indicative of a possible boundary within the milpa where different farmers were responsible for managing the fields to the north and south of Op. AI. Perhaps the farmer who managed the milpa closest to the plaza was more tolerant of wild and weedy plants compared to the one who managed the area farther away from the village. Variation in management of agricultural fields is also visible within the manioc fields south of the village. While the composition of the manioc beds differs greatly from both the home gardens and the milpas in that it was apparently monocultural, each manioc field was managed by individual cultivators and families, vertical growing system as evidenced by land use lines encountered in 2009 excavations . The land use lines were also aligned 30° east of north, just as the structures and milpas were. The community shares this dominant organizational scheme related to the importance of water coming from the river. Land was still subdivided into distinct plots with clear access by individual cultivators and households. Also found within the agricultural field excavations were quite large carbonized wood fragments from fallen branches in the middle of the maize fields, identified through anthracological analysis. The ancient Maya did not necessarily clear their land of all existing plants in order to grow their crops , so the practice of leaving some trees still standing in the middle of the fields should not be a surprise. We see at least two examples of large branches found within the agricultural fields, Terminalia buceras C. Wright, better known as the bullet tree , and Clusia sp., or what is known as matapalo .
These branches suggest that forest taxa were not completely eradicated in ancient Mesoamerican agricultural systems. T. buceras is considered a hard, durable wood so it is commonly used in construction, additionally tannin can be extracted from the bark . The black bark is used medicinally to treat skin eruptions . The wood charcoal from the T. buceras was located within Operation Y , located among the agricultural fields at Cerén and adjacent to a possible boundary marker between two maize fields. This marker was an eroded furrow that was not cultivated. Small eroded furrows throughout the milpas suggest a delineation of farming duties between the various households. This eroded surco could have possibly separated a northern from a southern section of the maize agricultural field. Since large quantities of T. buceras charcoal were recovered from this location, it is possible that the tree once stood near this location and could have also served as a boundary marker. The matapalo branches were recovered from Operation AD, again an agricultural context, and it lies just east of where the rubber tree branch fragments were found. The charred remains were recovered in a stratum of ash that would have been deposited after the Cerén inhabitants evacuated the village . Because of this, we know that these charred remains are part of a tree that remained standing until the very hot tephra [composing Unit 4] landed, with larger particles hotter than 575 °C . This species is known to have been used by Mesoamericans medicinally with the latex used to treat toothaches and the wood also has been used for construction and as a fuel source. The relationship between maize agricultural fields and forest systems is critical. Forest ecosystems attract many pollinators, so incorporating them within close proximity to agriculture, perhaps on the margins, can be extremely beneficial. Additionally, the accumulation of plant litter on forest floors can serve as fertilizer for agricultural systems and tree root systems can help prevent erosion . Ethnographic work in the Sierra Tarahumara shows that over seventy percent of food resources for communities in that region comes from forest ecosystems , so their incorporation into agricultural systems makes sense. Therefore, the indication of trees cultivated within the milpas at Cerén suggests that the ancient farmers valued the contributions of forest ecosystems within agriculture. Cerén’s agricultural fields were dynamic and incorporated a variety of species that were likely encouraged to grow and utilized for a variety of reasons, not just for food. It is possible that trees served as landmarks to differentiate land ownership and serve as a division between field plots.Farming is inherently knowledge intensive. This knowledge base is multi-faceted and context specific, and often informed by scientists, researchers, policymakers, government, extension agents as well as by farmers. While farmer knowledge is a critical component of this knowledge base, in the United States farmer knowledge has been widely underappreciated . Long considered “informal” knowledge, farmer knowledge is generally not regarded as scientifically valid and therefore infrequently recorded, whether formally or informally . Since the 1950s, due to an increase in knowledge standardization within production agriculture combined with widespread deskilling among farmers and farmworkers, farmer knowledge has become increasingly undervalued . However, farmers who practice alternative agriculture often amass an incredible wealth and depth of knowledge that integrates multiple ways of knowing and reflects diverse knowledge systems for thinking about evidence; perhaps most importantly, farmer knowledge is based in practice . If current trends in consolidation of land ownership, chemical-based intensification of agriculture, and standardization of farmer knowledge continue, local farmer knowledge may be endangered or permanently lost . Before this occurs, it is essential that we elevate the critical role of farmer knowledge and: 1) understand the key features of farmer knowledge; 2) understand the substance of farmer knowledge; and 3) systematically document farmer knowledge in specific local contexts.