The Chicha Soras valley on the boundary of Ayacucho with Apurimac in south-central Peru sees the introduction of intensive irrigated terraced agriculture in the Middle Horizon. The control over the water sources and the terracing systems fell to corporate lineage groups laying claim to common ancestors, viewed as being the founders of the local irrigation systems. The control over these systems and the rights of the respective lineages to land and water was expressed in the placement of ancestral tomb locations across the local landscape. This article demonstrates that ancestor-based organization of water sources was long lived across the area and survived the large-scale demographic and sociopolitical disruptions resulting from the Spanish conquest and the imposition of Christian belief systems.

While conducting archaeological survey to document the large prehistoric canal systems in the central portion of the Tehuacán Valley, investigators recorded a mound and plaza complex that includes what appears to be an effigy mound in the shape of a scorpion. Large quantities of ceramics, including surface-decorated and polychromes, indicate a Late Classic and Postclassic occupation. The site is interpreted as being part of an intensive agricultural system as it appears centrally located in the context of highly developed agricultural and irrigation infrastructure. For the reasons described, we interpret this ca. 60 meter scorpion effigy mound as an intentional feature with possible astronomical alignments. It is hypothesized as being part of a local civic/ceremonial complex with the possible use/function of observing the summer and winter solstices. If so, it provides an insight into the integration of calendrical ritual with the surrounding complex system of fields and irrigation canals. Admittedly, these observations and explanations are relatively subjective. However, we consider them to be persuasive when the evidence is considered in its entirety.

Redroot pigweed (Amaranthus retroflexus L.) is among the most troublesome weeds in the Intermountain West affecting corn (Zea mays L.) production and contributing to significant yield losses, in addition to losses caused by water stress. Improvements in agricultural technology such as use of drought-tolerant (DT) corn hybrids has helped minimize the impact of water stress on corn yields. However, it is not known how the use of hybrids affects the interactions between weeds and corn. This work evaluated the competitive effects of A. retroflexus on DT and drought-susceptible (DS) corn hybrids exposed to optimal and reduced irrigation levels in a semi-controlled study. The semi-controlled environment was established in a rainout shelter with corn maintained at a density of 66,482 plants ha−1 and A. retroflexus varied at densities of 0, 33,241, and 66,482 plants ha−1 that were then provided either optimal or reduced irrigation (100% and 50%). We observed a 45% reduction in the shoot biomass of DS corn under reduced irrigation, while the shoot biomass of DT corn remained the same under both irrigation levels in Season 1. In Season 2, both hybrids experienced a decrease in shoot biomass under reduced irrigation. Amaranthus retroflexus exhibited an 80% increase in shoot biomass when growing with DS corn exposed to reduced irrigation, compared with its growth with DS corn exposed to optimal irrigation. Conversely, DT corn negatively impacted A. retroflexus shoot biomass under reduced irrigation, resulting in only a 9% difference between the reduced and optimally irrigated plots. These findings suggest that DT corn may mitigate water stress while also providing the additional benefit of improved competition against weeds, effectively suppressing their growth in water-stressed environments.

Water and light are essential resources for crop development, and their limitations can significantly affect agricultural productivity. While irrigation systems are widely used to mitigate water scarcity, the role of nighttime artificial lighting in open-field conditions remains an emerging research area. This review explores the potential of nighttime light supplementation as a crop management strategy by analysing its physiological, morphological, and biochemical effects on plants. A key question addressed is whether supplemental lighting can enhance crop productivity in the field and under which conditions this approach is most effective. We examine which crops are more likely to benefit from artificial lighting based on their light limitations and physiological responses. Additionally, we discuss whether alternative agronomic practices, such as planting arrangements and canopy management, could achieve similar benefits without artificial light supplementation. The review also considers how the timing and spectral composition of supplemental light influence plant development. While continuous or nighttime lighting may alter physiological processes, it remains unclear whether these changes are beneficial or detrimental to productivity. Studies on light penetration, particularly the role of green and far-red wavelengths, suggest that spectral composition can impact plant morphology and light-use efficiency, raising questions about optimal lighting strategies. Finally, we address the feasibility of large-scale nighttime lighting in agriculture by discussing energy demands, potential environmental impacts, and economic viability. While preliminary studies suggest promising physiological responses, experimental validation under field conditions is still needed to determine whether this technology represents a profitable and sustainable investment.

In this paper we discuss laboratory experiments that address the problem of self-governance in an asymmetric commons dilemma. Small-scale irrigation systems that provide food for hundreds of millions of people around the world are probably the most common example of such dilemmas. Here, we formulate an abstract dilemma in which subjects make both a decision about investment in the provision of infrastructure associated with the use of a resource and about how much to extract from the common-pool resource made available by this infrastructure. The impact of inherent asymmetry in irrigation systems on the provision of a resource and the impact of communication on the capacity of the group to solve the two-level commons dilemma of cooperation and coordination based on the analysis of the experimental data are discussed.

The presence of excessive arsenic (As) in paddy fields poses a significant risk to human health due to its accumulation in rice grains. However, the current level of As in Sri Lankan paddy fields remains unclear. Therefore, this research aims to assess the distribution of exchangeable As concentration and investigate the effects of agro-climatic zones (ACZs), soil orders and water sources on exchangeable As concentration in Sri Lankan paddy fields. For this purpose, 7,154 soil samples were collected from paddy fields using a stratified random sampling method representing six ACZs, six soil orders and three water sources. Arsenic extraction was made using 0.01 M CaCl2 followed by the detection with inductive coupled plasma mass spectrophotometry. The concentration of exchangeable As ranged from 0.01 to 392.9 µg/kg with an average of 24.6 µg/kg. Samples from the Low-country Wet zone exhibited higher exchangeable As levels compared to those from the Low country Dry zone (P < 0.05). Among soil orders, Histosols, Inceptisols and Ultisols showed higher exchangeable As concentrations than Alfisols and Vertisols (P < 0.05). Rainfed paddy fields had higher exchangeable As compared to the fields with access to supplementary irrigation. Additionally, exchangeable As concentration was inversely correlated with soil pH and paddy grain yield (P < 0.05). The observed variations in soil-As concentration across ACZs, soil orders and water sources highlight the need for climate, soil order and water source-specific strategies to mitigate further accumulation of As in paddy fields.

In utero exposure to income shocks has a lasting effect on child well-being. In an agricultural economy, fluctuations in rainfall directly affect household income. In this paper, we investigate the short- and long-run impact of pre-pregnancy, prenatal, and early-life exposure to fluctuations in rainfall on height for a sample of 2290 children in rural Pakistan. Given the widespread canal irrigation system prevalent in the country, we also investigate how fluctuations in river water flows affect child health. We find that fluctuations in rainfall during the pre-pregnancy period have the most lasting effects on the stature of children in the short and long run. Exposure of a mother to a 1 standard deviation reduction in rainfall during the pre-pregnancy period led her child to be 0.17 standard deviations (0.53 cm) shorter by age four. This negative impact of a pre-pregnancy rainfall shock on height persisted over time; the child continued to be 0.12 standard deviations (0.83 cm) shorter, on average, by 13 years of age. However, we find that the effect of pre-pregnancy rainfall fluctuations on children’s height is smaller in districts that have access to irrigation facilities.

The aim of this work was to compare gas exchanges from leaf to whole plant scales, in two Ethiopian accessions (‘E083’ and ‘E027’), and two bred cultivars (Iapar 59 and Catuaí 99) of Arabica coffee (Coffea arabica L.) cultivated under irrigated and rainfed conditions. Variations in gas exchanges were evaluated over four phenophases (leaf expansion – BE1 and BE2, and berry harvesting – BH1 and BH2), covering the first two production years in the coffee life cycle. We addressed the following questions: Are gas exchanges modified by water availability at leaf and/or plant scales? Do bred cultivars and wild accessions differ in their physiological responses to water availability and phenophases? Photosynthesis (A), stomatal conductance (gs), and transpiration (E) were measured on the recently fully expanded leaves at the upper canopy stratum. The functional-structural plant modelling (FSPM) was used to integrate A at whole plant photosynthesis (A”p), based on 3D virtual trees constructed under VPlants modelling platform. Despite high A values of ‘E083’ overall phenophases, a strong decline in A”p under rainfed condition was observed due to lower plant leaf area as compared to irrigated condition. Catuaí 99 and ‘E083’ were more sensitive to drought than Iapar 59 and ‘E027’, considering photosynthesis at leaf and plant scales. At the last BH2 phenophase, A, gs, E, and carboxylation efficiency were similar between irrigated and rainfed conditions for all genotypes, suggesting some acclimation of leaf gas exchange to the environment. However, A”p benefited by water management in all phenophases as plant leaf area increased. These findings revealed the need to develop methodologies for structural and functional analyses at plant scale, an important step towards the realistic responses of plants and orchards to the surrounding environment.

Molybdenum (Mo) is an essential micronutrient for plants. However, Mo status in Sri Lankan paddy fields as affected by climate and soil is not known. This study was conducted to (i) determine the distribution of exchangeable Mo concentration, and (ii) examine the interactive effects of the agro-climatic zone (ACZ), soil order, water source, and their interactions in determining exchangeable Mo concentration in lowland paddy fields of Sri Lanka. A total of 3,719 soil samples representing six ACZs, six soil orders, and three water sources were collected using a stratified random sampling approach. Exchangeable Mo concentration was determined after extracting in 0.01 M CaCl2 solution and detected using inductively coupled plasma-mass spectrometry. Soil Mo concentration varied in the range of 0.01 to 245 µg kg−1 with a mean of 25.9 µg kg−1. Samples collected from the Wet zone, particularly Wet zone Low country, had higher Mo concentrations than those reported in other ACZs. Among the soil orders tested, Histosols had a higher Mo concentration while that in other soil orders was similar. Rainfed paddy fields had more Mo than supplementary irrigated paddy fields. Spatial maps were generated to visualise the geographical variation in soil Mo concentration. Due to the presence of a spatial heterogeneity of exchangeable Mo concentration, it is important to implement ACZ, soil, and water source-based strategies to improve Mo status in Sri Lankan paddy fields.