Abstract Perennial energy crops are promoted for soil carbon (C) sequestration, greenhouse gas (GHG) mitigation, and high biomass yields on marginal lands. Accurate field‐level GHG quantification is central to carbon intensity (CI) estimation. We quantified soil CO 2 and N 2 O fluxes over two growing seasons (2024–2025) in switchgrass ( Panicum virgatum L.) and corn ( Zea mays L.) on marginal land, partitioning total soil respiration (RT) into heterotrophic respiration (RH) and autotrophic respiration (RA) components by chamber‐based root exclusion. Cumulative RT was 47% greater in switchgrass than corn; RH did not differ between crops, indicating greater RA in switchgrass, and N 2 O emissions were 3.17‐fold lower. Biometric CI estimated from RH revealed switchgrass as a net soil C sink (−1.95 Mg CO 2 ‐eq Mg − 1 harvested biomass) and corn as a net source (+0.68 Mg CO 2 ‐eq Mg − 1 ). Without partitioning, RT‐based CI for switchgrass was near neutral (−0.02 Mg CO 2 ‐eq Mg − 1 ), confirming RH partitioning is necessary for accurate CI estimation in perennial energy cropping systems.
Abstract Nighttime satellite imagery has long served as a proxy for human development, equating light with progress and darkness with poverty. Here, we argue that this framing obscures a critical climate reality: the world's darkest regions, dominated by smallholder agriculture across central Africa, Southeast Asia, and the remote tropics, are simultaneously low‐emission zones and active carbon sinks, a dual function overlooked by Nationally Determined Contributions (NDCs), national Paris Agreement pledges for greenhouse gas reductions. Drawing on recent evidence that artificial light at night suppresses ecosystem carbon storage by accelerating nocturnal respiration, we identify a structural blind spot in global climate governance: as these regions urbanize, they will undergo a carbon double shock, losing sink capacity while rapidly becoming new emission sources. We propose that nighttime light data be integrated into NDC frameworks as an early warning tool to anticipate and govern this transition before it materializes in national emissions inventories.
Abstract Short‑stature (SS) corn ( Zea mays L.) hybrids represent an emerging phenotype with distinct morphological characteristics, but their performance under irrigated Mid‑South conditions is not well documented. We compared two SS hybrids (H1 and H2) and three tall‐stature (TS) hybrids (H3, H4, and H5) over two seasons. Grain yield differed among hybrids ( p < 0.01) and years ( p < 0.05), and hybrid × year interaction was not significant. Hybrid H4 (TS) yielded significantly more than H1 (SS), whereas H2 (SS), H3 (TS), and H5 (TS) did not differ from H1. Dry matter (DM) and ear traits, H3 and H4 (TS), accumulated more DM and produced more kernels per row, whereas H1 and H2 (SS) tended to have more rows per ear and heavier seed weight. Several traits showed hybrid × year interactions. Overall, two SS hybrids had yields not significantly different from two of the three TS hybrids, but broader validation requires multi‑location, multi‑year evaluation.
Understanding how management practices interact with environmental conditions is critical for stabilizing cotton yield and fiber quality. A 2-year field study (2024-2025) assessed the effects of tillage (conventional tillage [CT]; no-till [NT]), irrigation regime (all-row irrigation [ARI]; skip-row irrigation [SRI]), and planting density (7, 10, and 13 plants m- 2) on cotton (Gossypium hirsutum L.) yield and fiber quality. Year had the strongest influence on fiber quality, with 2025 producing fibers that were significantly longer (+2%), stronger (+3%), more uniform (+1%), but with poorer color grade (+12%) compared to 2024. Irrigation affected micronaire and color, as SRI reduced micronaire by 5%. NT increased seed cotton yield by 19%. Plant density influenced fiber quality through interactions; for example, plant density had an irrigation & times; plant density interaction for color grade. Overall, despite strong seasonal effects, context-dependent interactions among tillage, irrigation, and planting density indicated that management could contribute to fiber quality variation across years.
Organic grain systems can enhance soil organic carbon (SOC), but tillage may limit SOC gain, particularly in humid subtropical regions. We measured active and total SOC pools to 60 cm after 3 years in four organic grain systems differing in tillage and fertility. SOC stocks increased 30.3%-38.6% from baseline across depths, yet total SOC did not differ among cropping systems despite contrasting C inputs (9.4-22.2 Mg ha-1). At 0-5 cm, active C pools were the highest in the Ecologically Conscious System (ECS) characterized by reduced tillage, extended cover cropping, and C inputs of 18.5 Mg ha-1. Compared with the intensively tilled Maximum Yield System receiving 22.2 Mg C ha-1, ECS had 10.8%, 24.9%, and 28.5% higher permanganate-oxidizable C, water-extractable C, and microbial biomass C, respectively. These findings suggest that adjusting tillage and fertility strategies can promote early active C gains that may support long-term SOC accumulation.
