Previous research has shown the varied effect of earthworms on soil carbon dynamics. We carried out a 180-day incubation experiment with earthworms and maize residue additions under conventional tillage (CT) and no tillage (NT) system conditions to quantify the earthworm effect in the black soil of northeastern China. Earthworms did not affect soil CO₂ emissions, while residue addition significantly increased such emissions. The effects of earthworms on dissolved organic carbon (DOC) and microbial biomass carbon (MBC) gradually weakened with time in CT with and without residue addition, but gradually increased with time in NT with residue addition. In the CT system, earthworms accelerated the soil organic carbon (SOC) mineralization; and the newly added residue decomposed into SOC. In the NT system, earthworms accelerated the decomposition of native residues increasing the SOC content; this increase in decomposition rates by earthworms was greater than the inhibitory effect imposed by the addition of the new residue. Earthworms and residues combine to play a single role in CT and NT. This result will help in the understanding of the role of earthworms and residue in SOC dynamics, and in the development of management strategies to improve SOC.

Returning residue to soils is not only an effective nutrient management method, but also can reduce the air pollution caused by residue burning, which has become an important factor in global warming. However, it is not clear whether returning residue to the soil can affect the nitrogen mineralization and the nitrogen cycle process, and the environmental impact caused by the nitrogen loss in gaseous forms. Therefore, a pot experiment was conducted to study the effects of residue placement on the nitrogen turnover process, including microbial biomass N (MBN) and C (MBC), inorganic N, crop N uptake, and the contribution of residue-derived N to maize at different maize growth stages. Three treatments were assessed: no residue addition (T0), residue addition to the soil surface (T1), and residue incorporation into the 0–10 cm soil layer (T2). Soil samples were taken at the 0–5 and 5–10 cm layers for all residue treatments. Residue retention (T1 and T2) significantly affected the MBC and MBN contents and decreased MBC/MBN ratio at different maize growth stages. MBC/MBN markedly increased at the R1 stage compared to other growth stages. The differences in total inorganic nitrogen (TIN) were attributed to the balance in net N immobilization and net mineralization in the different maize growth stages. In addition, T2 significantly increased the residue-derived N source for maize by 11.3% compared to T0 in the R3 growth stage. Overall, relative to T1, T2 is a better agriculture management measure to promote N transformation and supply, and enhance residue-derived N release and uptake in maize.

Isolation of Vibrations Transmitted to a LIDAR Sensor Mounted on an Agricultural Vehicle to Improve Obstacle Detection.. Periu, C.F., A. Mohsenimanesh, C. Laguë and N.B. McLaughlin. LIDAR (LIght Detection And Ranging) technology can be used on autonomous agricultural vehicles for guidance and obstacle detection purposes. However, the quality of LIDAR measurements can be affected by mechanical vibrations induced by the operation of these vehicles on uneven terrain. The objective of this study was to develop a stabilizing system and to evaluate its effectiveness at reducing the transmission of mechanical vibrations to a LIDAR sensor installed on an agricultural tractor for the purpose of reducing the positioning error of obstacles during field operation. Special support bars (S) and stabilization system (SS) were designed for a SICK LMS 291-S14 LIDAR sensor mounted on an agricultural tractor. The positioning error of the sensor was assessed in field experiments by determining the difference between the known location of obstacles and their corresponding estimated locations from the sensor measurements. Increasing tractor speed had a negative effect on the accuracy of the sensor with an increase in the positioning error of up to 27%. The addition of the S system positively affected the accuracy of the sensor and resulted in a 41% decrease of the average positioning error from 340 to 201 mm. Finally, the addition of the SS system decreased the average positioning error by 57% from 382 to 161 mm. . On fait appel à la technologie LIDAR (détection et télémétrie par ondes lumineuses) pour assurer la navigation de véhicules autonomes ainsi que pour détecter de possibles obstacles. Dans le cas d’applications agricoles, les vibrations induites par les machines ainsi que par leur opération en terrain accidenté peuvent affecter l’efficience des systèmes LIDAR de façon négative. Cette étude visait à évaluer l’efficacité d’un système de montage et de stabilisation spécialement conçu pour réduire la transmission de ces vibrations à un capteur LIDAR installé sur un tracteur agricole dans le but de réduire les erreurs de localisation d’obstacles au champ. Des barres de support (S) et un système de stabilisation (SS) spécialisé ont été développés pour un capteur LIDAR SICK LMS 291-S14 utilisé pour la détection de quatre obstacles placés à différents endroits dans des champs agricoles. Un protocole expérimental a été mis en place pour évaluer les erreurs de localisation d’obstacles détectés par le capteur sous différentes conditions de terrain et d’opération. Ces erreurs de localisation ont été déterminée à partir de la différence entre la position exacte des quatre obstacles et leurs positions estimées correspondantes telles que déterminées par le capteur. Les résultats obtenus ont démontré que l’accroissement de la vitesse d’opération du tracteur a résulté en une réduction de la précision du capteur en raison d’un accroissement de l’erreur de positionnement atteignant 27%. L’ajout du système de support S a permis de réduire la valeur moyenne de l’erreur de positionnement de 41% (de 340 à 201 mm). Enfin, l’utilisation du système de stabilisation SS a résulté en une réduction de l’erreur de positionnement moyenne de 382 à 161 mm ou 57%. . CSBE/SCGAB Canadian Society for Bioengineering / Société Canadienne de Génie Agroalimentaire et de Bioingénierie. Provides information on and links to agricultural engineering, food engineering and biological engineering.