This work evaluated the debromination and uptake of ¹⁴C-labeled BDE-209 in rice cultivars grown in anoxic soil for 120 days (d) followed by cultivation of vegetables (peanut, eggplant and pepper) in oxic soil (120 d). Degradation of BDE-209 to lower polybrominated diphenyl ethers (PBDEs) occurred in cultivated soils, and more metabolites were released in oxic soil than in anoxic soil. The crop rotation from anoxic to oxic greatly enhanced the dissipation of BDE-209 in the soil (P < 0.05), in which the dissipation in anoxic soil planted with Huanghuazhan (HHZ, indica) and Yudao 1 (YD1, indica) were 6.8% and 2.4%, respectively, while in oxic soil with peanut and pepper were increased to 25.8% and 21.7%, respectively. The crop rotation also enhanced the degradation of BDE-209 in the soil, the recovered BDE-209 in soil after 120 d anoxic incubation with YD1 was 81.1%, but it decreased to 47.8% and 45.8% after another 120 d oxic incubation. Bioconcentration factors were between 0.23 and 0.36 for rice, eggplant and pepper but reached to 0.5 in peanut, which contains more lipids in the edible portion than the other test crops. The estimated daily intake for vegetables was 0.01–0.07 μg BDE-209-equivalent kg⁻¹ bw day⁻¹, which is at least two orders of magnitude below the maximum acceptable oral dose (7 μg kg⁻¹ bw day⁻¹). Our work confirms that crop rotation from rice to vegetable enhanced the dissipation and debromination of BDE-209 in the soil, and indicate that sequential anoxic-oxic rotation practice is considered to be effective in remediation of environmental pollutants.

To elucidate the origin of the wide-spread contaminations of plant derived commodities with various alkaloids, we employed co-cultures of pyrrolizidine alkaloid (PA) containing Senecio jacobaea plants with various alkaloid free acceptor plants. Our analyses revealed that all plants grown in the vicinity of the Senecio donor plants indeed contain significant amounts of the PAs, which previously had been synthesized in the Senecio plants. These findings illustrate that typical secondary metabolites, such as pyrrolizidine alkaloids, are commonly transferred and exchanged between living plants. In contrast to the broad spectrum of alkaloids in Senecio, in the acceptor plants nearly exclusively jacobine is accumulated. This indicates that this alkaloid is exuded specifically by the Senecio roots. Although the path of alkaloid transfer from living donor plants is not yet fully elucidated, these novel insights will extend and change our understanding of plant-plant interactions and reveal a high relevance with respect to the widespread alkaloidal contaminations of plant-derived commodities. Moreover, they could be the basis for the understanding of various so far not fully understood phenomena in cultivation of various crops, e.g. the beneficial effects of crop rotations or the co-cultivation of certain vegetables.

The potential for storing additional C in U.S. Corn Belt soils – to offset rising atmospheric [CO2] – is large. Long-term cultivation has depleted substantial soil organic matter (SOM) stocks that once existed in the region's native ecosystems. In central Illinois, free-air CO2 enrichment technology was used to investigate the effects of elevated [CO2] on SOM pools in a conservation tilled corn–soybean rotation. After 5 and 6 y of CO2 enrichment, we investigated the distribution of C and N among soil fractions with varying ability to protect SOM from rapid decomposition. None of the isolated C or N pools, or bulk-soil C or N, was affected by CO2 treatment. However, the site has lost soil C and N, largely from unprotected pools, regardless of CO2 treatment since the experiment began. These findings suggest management practices have affected soil C and N stocks and dynamics more than the increased inputs from CO2-stimulated photosynthesis. Soil carbon from microaggregate-protected and unprotected fractions decreased in a conservation tilled corn–soybean rotation despite increases in primary production from exposure to atmospheric CO2 enrichment.

Vegetable production in China is associated with high inputs of nitrogen, posing a risk of losses to the environment. Organic matter mineralisation is a considerable source of nitrogen (N) which is hard to quantify. In a two-year greenhouse cucumber experiment with different N treatments in North China, non-observed pathways of the N cycle were estimated using the EU-Rotate_N simulation model. EU-Rotate_N was calibrated against crop dry matter and soil moisture data to predict crop N uptake, soil mineral N contents, N mineralisation and N loss. Crop N uptake (Modelling Efficiencies (ME) between 0.80 and 0.92) and soil mineral N contents in different soil layers (ME between 0.24 and 0.74) were satisfactorily simulated by the model for all N treatments except for the traditional N management. The model predicted high N mineralisation rates and N leaching losses, suggesting that previously published estimates of N leaching for these production systems strongly underestimated the mineralisation of N from organic matter.

Carbon sequestration in agricultural soils is controlled by the balance of added organic residues and microbial oxidation of both residues and native organic matter (OM) as moderated by management and tillage. The PC-based model CQESTR predicts decomposition of residues, organic amendments and soil OM, based on cropping practices. CQESTR uses RUSLE (Revised Universal Soil Loss Equation) crop rotation and management practice, crop production, and operation databases. These data are supplemented with residue nitrogen and soil OM, bulk density, and layer thickness. CQESTR was calibrated with soil carbon data from 70-year-long experiments at the Research Center at Pendleton, OR. The calibrated model provides estimates with a 95% confidence interval of 0.33% OM. Validation at 11 independent sites resulted in a matching of observed with calculated OM with a 95% confidence interval of 0.55% OM. A 12th site, with a history of severe erosion, provided a poor match.

High ammonia (NH₃) emissions from fertilized soil in China have led to various concerns regarding environmental safety and public health. In response to China's blue skies protection campaign, effective NH₃ reduction measures need to consider both mitigation efficiency and food security. In this context, we conducted a meta-analysis (including 2980 observations from 447 studies) to select effective measures based on absolute (AV) and yield-scaled (YSAV) NH₃ volatilization reduction potential, with the aim of establishing a comprehensive NH₃ mitigation framework covering various crop production sectors, and offering a range of potential solutions. The results showed that manipulating crop density, using an intermittent irrigation regime for paddy field rice, applying N as split applications or partially substituting inorganic fertilizer N with organic N sources could achieve reductions in AV and YSAV reduction of 10–20 %; adopting drip irrigation regimes, adding water surface barrier films to paddy fields, or using double inhibitor (urease and nitrification), slow-release or biofertilizers could achieve 20–40 % mitigation; plastic film mulching, applying fertilizer by irrigation or using controlled-release fertilizers could yield 40–60 % reduction; use of a urease inhibitor, fully substituting fertilizer N with organic N, or applying fertilizer by deep placement could decrease AV and YSAV by over 60 %. In addition, use of soil amendments, applying suitable inorganic N sources, or adopting crop rotation, intercropping or a rice-fish production model all had significant benefits to control AV. The adoption of any particular strategy should consider local accessibility and affordability, direct intervention by local/government authorities and demonstration to encourage the uptake of technologies and practices, particularly in NH₃ pollution hotspot areas. Together, this could ensure food security and environmental sustainability.

In winter wheat (Triticum aestivum L.)-summer maize (Zea mays L.) rotation system in the North China Plain, maize roots do not extend beyond 1.2 m in the vertical soil profile, but wheat roots can reach up to 2.0 m. Increases in soil nitrate content at maize harvest and significant reductions after winter wheat harvest were observed in the 1.4-2.0 m depth under field conditions. The recovery of 15N isotope (calcium nitrate) from various (1.0, 1.2, 1.4, 1.6, 1.8 and 2.0 m) soil depths showed that deep-rooting winter wheat could use soil nitrate up to the 2.0 m depth. This accounted partially, for the reduced nitrate in the 1.4-2.0 m depth of the soil after harvest of wheat in the rotation system. Deep-rooted wheat can recycle nitrate leached from maize root zone in winter wheat-summer maize rotation system.

Clearfield® wheat (Triticum aestivum) have helped eliminate the toughest grasses and broadleaf weeds in Spain since 2005. This crop production system includes other tolerant cultivars to the application of imidazolinone (IMI) herbicides. However, the continuous use and off-label rates of IMI herbicides can contribute to the development of resistance in Lolium rigidum and other weed species. In this research, the main objectives were to study the resistance mechanisms to acetolactate synthase (ALS) and acetyl coenzyme A carboxylase (ACCase) inhibitors in a L. rigidum accession (LrR) from a Clearfield® wheat field, with a long history rotating these IMI-tolerant crops and compare them with those present in the IMI-tolerant wheat. The resistance to ACCase inhibitors in LrR was due to point mutations (Ile1781Leu plus Asp2078Gly) of the target site gene plus an enhanced herbicide metabolism (EHM), on the other hand, in wheat accessions was due only by EHM. Mechanisms involved in the resistance to ALS inhibitors were both point mutations of the target gene and EHM in the IMI-tolerant wheat, while only evidence of mutation (Trp574Leu) was found in the multiple herbicide resistant L. rigidum accession. This research demonstrates that if crop rotation is not accompanied by the use of alternative sites of action in herbicide-tolerant crops, resistant weeds to herbicide to which crops are tolerant, can easily be selected. Moreover, repeated and inappropriate use of Clearfield® crops and herbicide rotations can lead to the evolution of multiple resistant weeds, as shown in this study, and have also inestimable environmental impacts.

The fate of the ¹⁴C-labeled herbicides ethidimuron (ETD), methabenzthiazuron (MBT), and the fungicide anilazine (ANI) in soils was evaluated after long-term aging (9–17 years) in field based lysimeters subject to crop rotation. Analysis of residual ¹⁴C activity in the soils revealed 19% (ETD soil; 0–10 cm depth), 35% (MBT soil; 0–30), and 43% (ANI soil; 0–30) of the total initially applied. Accelerated solvent extraction yielded 90% (ETD soil), 26% (MBT soil), and 41% (ANI soil) of residual pesticide ¹⁴C activity in the samples. LC-MS/MS analysis revealed the parent compounds ETD and MBT, accounting for 3% and 2% of applied active ingredient in the soil layer, as well as dihydroxy-anilazine as the primary ANI metabolite. The results for ETD and MBT were matching with values obtained from samples of a 12 year old field plot experiment. The data demonstrate the long-term persistence of these pesticides in soils based on outdoor trials.

Arsenic (As) is a toxic metalloid associated with various negative human health impacts including cancer, skin lesions, cardiovascular diseases, and diabetes. Arsenic contamination of groundwater and soil is a major human health issue, particularly in South and Southeast Asia. Use of As-contaminated groundwater from shallow tube wells for irrigation of paddy rice, the staple food for people in this region, is one of the causes of As-related health impacts. The anaerobic growing conditions of flooded rice paddies and the unique physiology of the rice plants lead to increased As levels in rice. The World Health Organization (WHO) has set advisory levels of As in polished (i.e., white) rice grain at 0.2 mg/kg, but the EU and USA are yet to set legal standards for As in rice and rice-based products. Strategies for lowering As accumulation in rice revolve around two approaches—agronomic and biotechnological. Agronomic approaches, such as mineral supplementation of soil using iron, phosphorus, sulfur, silicon, water management, soil aeration practices, and the use of biological agents, are designed to lower As solubility, and uptake by rice. Rotation of the rice crop with As accumulating plants could also result in lowering soil As. Biotechnological approaches involve producing transgenic rice varieties by altering the expression of genes involved in As uptake, translocation, and sequestration in the plant. These approaches, combined with proper diet management and creating public awareness on potential health risks resulting from chronic exposure to As in rice, could play a key role in risk reduction.