Maize Agriculture Research Articles

Agribusiness System and Maize Agriculture Development Strategy in Palolo District Sigi Regency

Maize productivity in Palolo District only reaches 4.8 tons/ha, far below the national average. Suboptimal cultivation techniques, limited access to superior seeds, and the use of fertilizers and pesticides that are not in accordance with the recommendations. Farmers' limited knowledge of modern agricultural practices and lack of access to technology and training also affect production yields. A synergistic agribusiness system ensures integration between the upstream and downstream sectors. The purpose of this study is to analyze the success of the maize agribusiness system and formulate a strategy for the development of the maize agribusiness system. The sampling technique is purposive sampling. The analysis method uses agribusiness index, SWOT analysis and AHP. As a result of the calculation of the agribusiness system index, the value obtained is 11.4 from the maximum value of 17.4 or 65.5%. It shows that the maize agribusiness system is running well, in a good value interval (8.71-17.40). As a result of the SWOT and AHP analysis, there are four main strategies for the development of maize agribusiness: Improving farmers' skills through training and mentoring the latest agricultural technology (weight 0.225), optimizing land use and maximizing production (weight 0.219), increasing maize productivity with active extension and technological innovation (weight 0.137), increasing productivity and availability of facilities through the adoption of sustainable agricultural practices and environmentally friendly technology (weight 0.106).

Challenging the Atacama desert: Agronomic and water conditions for pre-Hispanic maize agriculture in hyper arid environments inferred by δ18O isotopes

During the Formative Period (ca.2400–950 years BP), pre-Hispanic farmers in Pampa del Tamarugal developed a complex agricultural system in the hyper-arid Atacama Desert in Tarapacá, northern Chile. This system involved numerous agricultural fields congregated near the Tarapacá Valley’s perennial stream and the Guatacondo ravine’s ephemeral stream. Well-established villages such as Caserones, Pircas, Ramaditas, and Guatacondo accompanied these developments. However, the importance of understanding the water sources has been neglected despite the efforts to understand the relationships between pre-Hispanic agriculture and their living environment. Thus, we presumed the use of local water sources without a clear understanding of their exploitation methods or the associated technological implications. Furthermore, there is limited research on groundwater use in Tarapacá. This research aims to understand water sources used in the cultivation of maize (Zea mays) using δ18O isotope values obtained from pre-Hispanic maize kernels in Tarapacá. We compared these values with published δ18O values of water sources and applied a generalized linear model (GLM) with a Gaussian distribution, performing a Tukey’s post hoc test for multiple comparisons of means with heteroscedasticity-consistent covariance estimation. The best-fit model was identified using a stepwise model selection procedure based on the Bayesian information criterion (BIC). Our results indicate that mean δ18O values of organic matter from maize kernels range from 24.73 ‰ to 31.65 ‰. The best performing model on δ18O only included Group (BIC=298.2) as the explanatory variable as Period, Site, and Weight had no effects. These findings point towards a significant statistical relationship between the δ18O values of organic matter derived from maize kernels and the specific geographic regions they originate from. These values also show an enrichment of δ18O isotope in Tarapacá samples, except for Pica 8. These results indicate diverse agricultural strategies that utilized different water sources including perennial flow in the Tarapacá River, ephemeral runoff at Guatacondo, and groundwater in the Pampa del Tamarugal. Also, due to the enrichment of δ18O, we suggest that the circular structures found among the fields were used as water reservoirs leading to the observed enrichment of δ18O isotope values. We discuss the role of ancient agriculture technology in water management, the role of maize, cultural strategies, and the relationships with their environment. In conclusion, pre-Hispanic farmers managed limited water sources successfully despite intermittent drought for hundreds of years until the 1970 s, when agriculture was abandoned due to multiple factors.

The Fremont Frontier: Living at the Margins of Maize Farming

Abstract The Fremont provide an important case study to examine the resilience of ancient farmers to climatic downturns, because they lived at the far northern margin of intensive maize agriculture in the American West, where the constraints on maize production are made abundantly clear. Using a tree-ring and simulation-based reconstruction of average annual precipitation and maize growing degree days, along with cost-distance to perennial streams, we model spatial variability in Fremont site density in the eastern Great Basin. The results of our analysis have implications for defining the ecological envelope in which farming is a viable strategy across this arid region and can be used to predict where and why maize farming strategies might evolve and eventually collapse as climate changes over time.

Isotopes and bioarchaeology in the Andes: Diet, life histories, and ritual

AbstractIn this article, we present an isotopic perspective of key research questions in Andean bioarchaeology, focusing on the ways in which stable and radiogenic isotope analyses have contributed to our understanding of the past. Andean archaeology offers a window into long‐term processes of economic, socioecological and political change since the mid‐Holocene, thus providing historical trajectories of socio‐ecological change relevant for global comparison. The spatial scale of this review includes the areas traditionally identified as the south‐central Andes and the southern Andes. These ecological scenarios are characterised by marked topographic, climatic and ecological variations that are fruitful for the application of isotopes to understand diet, mobility, migration and ritual in past human societies. Within the broader Andean context, here we focus on the growth of bioarchaeological applications of isotopic data. We discuss some major themes of economic production, mobility and exploitation of environmental diversity, maize agriculture, migrations in small‐ and large‐scale societies and ritual practices related to human sacrifices and body modifications. Building on this, we discuss theoretical and methodological trends and directions for future research combining bioarchaeology and isotopes in the Andes.

Salinity Stress in Maize: Consequences, Tolerance Mechanisms, and Management Strategies

Maize, along with rice and wheat, is a popular staple food crop worldwide, and the most widely produced cereal crop. It is a versatile crop that may be utilized as a source of raw materials for human and animal fodders. Low agricultural yield and rapid population expansion significantly threaten future food security. Maize production is hampered by biotic and abiotic causes, with abiotic factors being the most critical limitation to agricultural output worldwide. Soil salinity is a key abiotic factor that reduces agricultural production by imposing negative impacts at several life cycle phases, including germination, seedling, vegetative, and reproductive development. Maize plants experience many physiological changes due to osmotic stress, toxicity of particular ions, and nutritional imbalance induced by salt stress. The degree and duration of stress, crop growth phases, genetic characteristics, and soil conditions influence yield reduction. Maize plants can tolerate salt stress involving a complex mechanism by changing their physiological, biochemical, and metabolic activities like stomatal functioning, photosynthesis, respiration, transpiration, hormone regulation, enzymes, metabolite generation, etc. After studying the salt tolerance mechanisms of maize plants under stress, integrated management techniques should be developed for maize agriculture in saline settings. Therefore, the study of plant responses to salt stress, stress tolerance mechanisms, and management strategies is one of the most imperative research fields in plant biology, and the study will focus on the effects of salt stress in different growth stages, plant tolerance mechanisms, and agronomic management practices for successful maize production all over the world.

Pre-Mamom Pottery Producers in the Heart of the Yucatan Peninsula

Recent research in the Maya Lowlands has revealed substantial new evidence for the first pottery producers at about 1000-600 bc, during the early Middle Preclassic period. This comparatively late adoption is a special case in Mesoamerica, where pottery appeared elsewhere up to a millennium earlier. Although archaic lifeways had long been established in the region, and pottery technology was likely known to some archaic communities, these new data reveal the complex set of circumstances that prompted the shift to ceramic production across the Yucatan Peninsula, Peten, and Belize. This article reviews these data from the perspective of the upland region of central and southern Yucatan, known as the Elevated Interior Region (EIR). Its rather complex early settlement links the EIR to contemporary pottery industries throughout the peninsula, suggesting well-established exchange systems were in place even as the first populations chose to settle more permanently on the landscape. Most significant among these cultural shifts was the increasing dependence on maize foodways as a primary subsistence strategy. Intensive maize agriculture has not been documented in Mesoamerica much before 1000 BC, yet ceramic technology was adopted independent of its use in other areas. Current evidence suggests, however, that the two were linked in the Maya Lowlands, where a relatively rapid transition took place as horticultural communities became more dependent on maize crops, followed waterways to settle more permanently on the landscape, and began producing pottery locally.

Effect on biomass production and phosphorus use efficiency of maize by using citric acid amended di-ammonium phosphate fertilizer

Phosphorus (P) is a critical factor influencing maize (Zea mays L.) development and yield. To explore the influence of P on maize growth, a pot experiment was conducted during the summer of 2021. There were five treatments T1 = No DAP/CA, T2 = 5 ml (80 mg kg−1 soil) DAP, T3 = 5 ml (120 mg kg−1 soil) DAP, T4 = 5 ml (80 mg kg−1 soil) DAP and 2 mM citric acid, T5 = 5 ml (120 mg kg−1 soil) DAP and 2 mM citric acid. Citric acid-amended P fertilizers (i.e., CA and DAP) exhibited significant effects (p < 0.05) on all the parameters studied in comparison to the sole application of DAP. Among phosphorus fertilized treatments, the DAP 120 + CA produced significantly higher biomass yield (16.37 g pot−1), while sole DAP 80 produced lower biomass (10.61 g pot−1); the DAP 120 + CA produced significantly higher plant length (34.273 cm), while sole DAP 80 produced lower plant length (30.467 cm); DAP 80 + CA produced significantly higher phosphorus recovery (25.583%), while sole DAP 120 produced lower phosphorus recovery (19.863%); DAP 120 + CA showed significantly higher phosphorus use (69.565 mg plant-1), while sole DAP 80 showed lower phosphorus use (39.154 mg plant-1); the highest total PUE (40.503%) was recorded in DAP 120 + CA treatment, while sole DAP 80 treatments showed lower PUE (22.743%); and the highest PCN (4.25 mg g-1) was recorded in DAP 120 + CA treatment while sole DAP 80 treatments showed lower PCN (3.69 mg g-1). In conclusion, the use of citric acid-amended P fertilizers (CA and DAP) significantly improved all parameters studied, compared to the sole application of DAP. The DAP 120 + CA treatment showed the highest values for biomass yield, plant length, phosphorus recovery, phosphorus use, total PUE, and PCN, while the sole DAP 80 treatment showed lower values for these parameters. The findings suggest that growing maize using citric acid-amended DAP could be more beneficial to get a higher crop yield of maize. Thus, fertilizer application in maize agriculture can be a technique for boosting both economic and environmental profitability.

Grey water footprint of crop in Riau Province

The escalating severity of the water problem poses a potential threat to the prospects of sustainable development in the future. The grey water footprint is an indicator of the need for fresh water to mix and dilute pollutants and maintain air quality according to water quality standards. The evaluation of the grey water footprint (GWF) serves as a valuable measure in the mitigation and management of water contamination. The main objective of this study is to determine the grey water footprint associated with crop production along the Kampar Watershed and develop strategies to mitigate pollution levels. The grey water footprint is calculated using a water footprint assessment method. The finding show that the grey water footprint of rice farming (17.01 m3/ton) is larger than the maize (9.51 m3/ton), this indicate that necessary to improve water management on rice and maize agriculture. The water footprint performance scores of rice and corn plants are both in the poor category with scores of 11.93 and 45 respectively. To improve grey water performance and reduce air pollution, it can be done by using fertilizer according to plant needs, replacing inorganic fertilizer with organic fertilizer, implementing practices conventional tillage and maintain soil moisture.

Enduring Legacies of Agriculture: Long-term Vegetation Impacts of Ancestral Menominee Agriculture, Wisconsin, USA

Agriculture significantly reshapes soils and ecology, often with lasting ecological impacts. For over a millennium, the Menominee Indian Tribe of Wisconsin have practiced maize agriculture in the upper Great Lakes. Though the vast majority of ancestral Indigenous agricultural sites have been destroyed in the American Midwest, the Menominee have documented numerous archaeological, raised garden bed sites at their Reservation, enabling an investigation into the lasting vegetation impacts of ancestral Menominee agricultural practices. Here, we report findings from our pilot vegetation surveys of three ancestral raised garden bed sites. Results show that all sites surveyed are high quality ecosystems. We observed differences in species richness between agricultural and non-agricultural places, although findings varied based on location. Overall, our surveys illustrate the complexity of these anthropogenic, biologically diverse landscapes shaped by past and contemporary Menominee land use and illustrate how today’s ecology is in part an enduring legacy of past practices.

The Goldilocks Zone for maize agriculture and the settlement and abandonment of the West Tavaputs Plateau

Between 2100 and 500 BP, maize farming spread throughout the American Southwest, driving changes in land use patterns and relative increases in the number of archaeological sites, which is commonly interpreted as increases in population. In the context of the Southwest, with its variable topography and limited water sources, the locations suitable for productive maize agriculture are limited. Higher elevation locations often have a greater abundance of water, both in the form of precipitation and perennial water sources but lack the growing season lengths required for maize farming. Lower elevation locations have the long growing seasons required for maize, but often have higher evaporation rates corresponding with higher temperatures, and thus decreased soil moisture retention. The relationship between elevation and maize agriculture is well recognized, and locations where both growing season length and moisture requirements can be met serve as a Goldilocks Zone in which maize farming is possible. Here, we use a regional approach to model the Goldilocks Zone for maize farming in Utah, and then contextualize patterns of settlement and abandonment on the West Tavaputs Plateau (WTP) in east-central Utah. We use archaeological sites with direct evidence of maize cultivation, modern growing degree days estimates, and modern estimates of moisture abundance to bracket the prehistoric maize farming niche in Utah. Then, we apply the model to archaeological data from the WTP to test hypotheses derived from the Ideal Free Distribution model about the effects population and precipitation changes had on prehistoric land use patterns of settlement and abandonment, and whether the patterns of settlement and abandonment differ from one another. We find that a) population drives land use patterns in the WTP, but not in the way we originally hypothesized, suggesting there is an important decision variable missing from our model, which may pertain to the specific topographic setting of the WTP and the distribution of its water sources, b) precipitation has no effect on land use patterns suggesting that maize agriculture on the WTP was dependent on irrigation, and c) that patterns of settlement and abandonment seem to mirror each other.

Response of diatom communities to climate and human disturbance: A 4200-year record from Costa Rica

This study integrates diatom analysis with existing records of pollen, charcoal, elemental composition, and stable light isotopes to expand upon the 4200-year history of human activity and climate change from Laguna Los Mangos in southern Pacific Costa Rica. We counted diatoms in peroxide-treated samples and analyzed community composition using cluster analysis, revealing four distinct assemblage zones with diatom variability most closely correlated with phosphorus, titanium, and organic content. The earliest assemblage (Zone D, 4150–3430 cal yr BP) was dominated by Encyonema silesiacum and Nitzschia incognita and aligned with a period of deforestation, erosion, and abundant macrophytes. Gomphonema affine proliferated in Zone C (3430–2450 cal yr BP), reflecting increased pH and productivity likely caused by agriculture-induced nutrient loading. We attributed the preservation gap from 3290 to 2970 cal yr BP in Zone C to silica depletion and erosional deposition that induced decline in diatom abundance by diluting valve concentrations in lake sediments. Nitzschia incognita and G. affine became the dominant taxa in Zone B (2450–1400 cal yr BP), likely reflecting eutrophy, increasing conductivity, and drying climate. Dominance of Diadesmis confervacea indicated reduced lake level in Zone A (1400 cal yr BP–modern) at the onset of the Terminal Classic Drought (TCD). A hiatus in the record indicates lake desiccation from 950 to 450 cal yr BP. During the Little Ice Age (LIA), diatoms reflect conditions similar to Zone B indicating increased lake level, circumneutral pH, and eutrophy. Refilling of the lake indicates increased precipitation during the LIA despite evidence of severe regional drought reported at other sites. Variable precipitation during this period likely resulted from the combined effects of Spanish contact, agricultural collapse, forest recovery, and shifts in Atlantic and Pacific climate forcing mechanisms. Overall, the Los Mangos diatom record reflects shallow, slightly alkaline, eutrophic conditions influenced by nutrient enrichment, erosion, and deforestation associated with maize agriculture.

Sourcing Mississippian pottery among the complex maritime cultures of Florida’s peninsular Gulf coast

In eastern North America after ca. AD 1050, the spread of Mississippian cultures sparked widespread transformations to economy, material culture, political structure, and ideology. “Mississippianization” influenced the politically complex maritime polities of Florida’s peninsular Gulf coast, but the lack of maize agriculture indicates changes played out differently than among many inland polities. Mississippian-style pottery sherds deposited widely in mounds and in middens at the largest administrative centers are perhaps the clearest evidence of connections to the Mississippian world. We conducted a provenance study using neutron activation analysis of 303 Mississippi Period pottery vessels from 18 sites on Florida’s peninsular Gulf coast to investigate how and from where coastal communities acquired Mississippian vessel forms, paste recipes, and iconography. The sample includes numerous Mississippian-related pottery types as well as Pinellas Plain, one of the local utilitarian wares. Four chemical groups are defined, three of which are local to the peninsular Gulf coast and one that is associated with the “Deep South,” defined here as the inland Florida panhandle and Chattahoochee River area of southern Georgia. Our results indicate that most Mississippian-style vessels were locally made but used clay sources different from some utilitarian wares such as Pinellas Plain. Using distinctive clays and paste recipes, local production of Mississippian vessels may have been controlled by competing kin-based corporate groups affiliated with each mound center. The widespread low frequency of nonlocal Mississippian sherds from the Deep South shows persistent connections to inland Fort Walton and Rood Phase polities, possibly in relation to training of coastal potters. A greater prevalence of pottery from the Deep South at Shell Creek (8LL8) at the southern edge of the sampling region may reflect a polity with greater success in acquiring prestige goods, perhaps associated with the strong and expansive political power of the Calusa.

“It is pure criollo maize”: seeds, chemicals, and crop classifications in San Miguel del Valle, Oaxaca, Mexico

ABSTRACT Although substantial literature has discussed the centrality of traditional maize agriculture to food security and culture in Mexico, little attention has been paid to how small-scale Mexican farmers classify their seeds and foods. This article draws on ten months of ethnographic field work about maize agriculture in San Miguel del Valle (San Miguel), a Zapotec community in Oaxaca, Mexico. Local agriculture in San Miguel no longer provides the majority of locally consumed food, but it still fundamentally shapes life in the community. I describe how residents categorize their foods and crops based on locality and knowledge about production. The term criollo, commonly used to refer to native crop varieties, is used to express adherence to local standards of production. Ideas about chemicals are important in residents’ evaluations of quality. The ways in which residents discuss their lands and foods in Zapotec reflect relationships between locally produced foods, health, and the human body. The value of local production for San Miguel residents entails not just the origin of foods, but also production standards, the ability to know how the food was produced, and perceived effects on health.

Reevaluating Mobility and Sedentism in Classic Mimbres and Salado Villages, Southwest New Mexico

Fourteenth-century Cliff phase Salado (AD 1300–1450) villages in southwest New Mexico show interesting contrasts with earlier villages in the same region from the Classic Mimbres period (AD 1000–1130). One of the most intriguing differences is that although people in both time periods relied heavily on maize agriculture, Salado period villagers may have employed a more mobile land-use strategy in comparison to Classic Mimbres period residents of the same areas. Researchers in the 1980s suggested that “short-term sedentism” characterized Salado period sites but had limited comparative data. This study reexamines evidence for mobility and sedentism in the Classic Mimbres and Salado periods using burial and architectural data from 49 excavated archaeological sites in the Mimbres region, including recent work on Salado villages.

Maize Landraces and Drought: Seed Systems in San Miguel del Valle, Oaxaca, Mexico

Maize diversity in southern Mexico is threatened as climate change and sociopolitical factors limit the ability of small-scale farmers to continue agricultural production. Between 2017 and 2019, I conducted ten months of ethnographic research on maize agriculture in San Miguel del Valle (San Miguel), a Zapotec community in the Central Valleys of Oaxaca. In San Miguel, agricultural production is declining due to seasonal droughts that have increased in frequency and intensity in recent generations. Farmers who continue to plant maize use exclusively their own or locally acquired seeds of native landraces. Worsening seasonal droughts play a significant role in determining what seeds farmers plant and whether farmers choose to continue planting. Farmers plant locally sourced seeds partly because they believe these to be the only available seeds that will produce a harvest in their fields. This points to important interactions between environmental conditions, seed choice, and farmers' livelihoods. I contribute to existing literature on maize diversity and in situ conservation by using an ethnographic approach to describe seed saving practices and networks in San Miguel.

A data mining approach gives insights of causes related to the ongoing transgene presence in Mexican native maize populations

ABSTRACT Mexico is the center of origin of maize and one of the phenomena that imperil maize conservation is transgene presence. Although previous studies have documented transgene presence in Mexican landraces, to date there is no countrywide transgene monitoring protocol, nor systematic analyses assessing which factors could be related with transgene presence and dispersal. In this work, we propose a geographically representative sampling protocol and present empirical data from three sampled states: Mexico City, Oaxaca and Chiapas. To further investigate which environmental and social variables could be associated with transgene presence, we carried out a data mining approach. To assess transgene presence in collected maize samples, we used Real-Time PCR, finding that transgenes were widely distributed across sampled localities: 33% of the localities in Chiapas, 25% in Mexico City and 11% in Oaxaca. The data mining approach allowed us to identify state-specific spatial associations in Chiapas and Oaxaca. In Chiapas, a higher probability of transgene presence appeared related to the coexistence of industrialized maize agriculture, while in Oaxaca it was related with seed exchange. We discuss the importance of implementing a national biomonitoring protocol to increase our understanding of the sources that enable transgene presence and dispersal.

A RADIOCARBON CHRONOLOGY FOR ESTADIO DE QUILLOTA IN THE ACONCAGUA VALLEY, CENTRAL CHILE, WITH REFERENCE TO THE ADOPTION OF INTENSIVE MAIZE AGRICULTURE AND REVISITING THE TIMING OF INKA INFLUENCE ON THE SOUTHERN FRONTIER

ABSTRACTEstadio de Quillota (EDQ) is the largest known pre-Columbian cemetery site within the Aconcagua Valley of Central Chile. Despite its importance, existing chronological data for EDQ are limited and questions remain regarding the prehistory of the Valley, particularly around the adoption and intensification of maize agriculture, as well as the timing of Inka influence reaching the region. Seventeen new AMS radiocarbon dates presented here indicate two distinct phases of use at EDQ: An earlier phase (339–196 cal BC to cal AD 128–339), and a later phase (cal AD 1280–1387 to cal AD 1413–1458). Accompanying stable isotope (δ13C and δ15N) analyses of human bone collagen (n=22) demonstrate diachronic dietary changes corresponding to these phases, with a reliance on terrestrial C3 resources during the earlier period, followed by a heavy dependence on C4-based (maize) resources during the later use. Bayesian modeling of the dates from Late Period contexts suggests Inka influence arrived in Central Chile by ca. cal AD 1400, decades before the date cited in traditional chronologies, AD 1471. Inka expansion likely occurred here with an initial phase of interaction and exchange preceding a later phase of integration. This finding supports growing evidence that the traditional chronology of the Inka Empire requires reconsideration.

Late Woodland settlement ecology of the Appalachian Summit

ABSTRACT The Late Woodland (ca. AD 800–1500) was a time of socioeconomic and environmental change in the Appalachian Summit. Changing climatic conditions and the introduction of maize agriculture made permanent settlement in these high-elevation mountain landscapes possible for the first time. We adopt a settlement ecology approach to examine how Late Woodland communities situated themselves in the landscape. Drawing upon geospatial analyses of legacy datasets, we document how Late Woodland communities prioritized access to different socioeconomic resources in the New River Headwaters region of northwest North Carolina. The New River Headwaters was an important source of natural resources, including mica and copper, as well as an important corridor for the movement of people and resources throughout Eastern North America. Our analyses demonstrate that Late Woodland communities balanced access to arable land, copper sources, and long-distance trade routes when situating their settlements. Larger sites had access to more land suited for maize agriculture than smaller sites. The largest sites in the region were also well-positioned with nearby access to copper sources and trade routes along the New River. Regional approaches to Late Woodland occupation in the Appalachian Summit reveal the dynamic relationship between humans and the environment in mountain landscapes.

Strengthening Community through a Traditional Haudenosaunee Diet

The Haudenosaunee Peoples of Eastern North America share a strong pastoral tradition and culture associated with maize agriculture. Traditional dietary practices were severely disrupted by colonial practices, and over time this has led to increased burdens of chronic diseases such as type 2 diabetes and obesity. To lead meaningful Traditional dietary practices, Haudenosaunee community members mobilized to develop and promote a 90-day challenge called ‘Healthy Roots.’ The Healthy Roots Program prioritizes Traditional Haudenosaunee foods found in territories during pre-contact times. The community decided to officially evaluate the impact of the dietary program using a pilot pre–post evaluation study (International Journal of Indigenous Health, 2021). We created the following digital story to capture the experiences and perspectives of the first cohort of community members to enroll in the Six Nations Healthy Roots Research Study. The film team attended six community meetings between February 2017 and October 2017 to capture the stories of participants before, during, and after the completion of the Healthy Roots Program. *Private Media Link for Video: https://bit.ly/3EJnsJO

Compound-specific stable carbon and hydrogen isotope analyses of late-Holocene vegetation and precipitation change at Laguna Los Mangos, Costa Rica

New compound-specific isotope analyses of a sediment core from Laguna Los Mangos in southern Pacific Costa Rica improves understanding of late-Holocene precipitation change in a region with limited paleoprecipitation records that is vulnerable to future climate change. We established paleoprecipitation and paleovegetation records from compound-specific stable hydrogen and carbon isotopic compositions of terrestrially-derived n-alkanes (δ2Halkane and δ13Calkane) to assess paleohydrologic variability and potential linkages to paleoecological change and human activity as revealed by prior analyses of the Los Mangos core. The δ2Halkane values were corrected for isotopic fractionation using pollen counts from the same core. The Los Mangos record extends to 4200 cal yr BP and small increases in δ13C values of C29, +0.6‰, and C31 alkanes, +0.3‰, (δ13CC29, 31) indicate a slight increase in C4 vegetation after initial introduction of maize agriculture to the watershed at ca. 3360 cal yr BP. This slight increase in C4 vegetation is followed by the largest positive carbon isotope excursions in the record, as compared to record averages (δ13CC29 = +3.2‰, δ13CC31 = +5.0‰). Paleohydrologic variability likely influenced vegetation and human activity at Los Mangos. Lake desiccation during the late-Terminal Classic Drought (TCD) resulted in a sedimentary hiatus in the Los Mangos record from ca. 950 to 450 cal yr BP. Positive excursions in comparison to record averages occur for both δ2HC29 and δ2HC31 proxies (δ2HC29 = +25.3 to +13.4‰ and δ2HC31 = +6.5‰) during the middle Little Ice Age (LIA) and indicate drier than average conditions, but there is no evidence of desiccation during this period. Thus, drought conditions during the LIA were apparently not as severe at Los Mangos as during the TCD, possibly because of differing forcing mechanisms for LIA climate that originated, or were more clearly expressed, in the Atlantic basin.