Rice-crayfish pattern in irrigation-drainage unit increased N runoff losses and facilitated N enrichment in ditches.

The rice-crayfish (RC) integrated pattern has been developed vigorously in China, but how it affects the nitrogen (N) runoff loss and distribution status during rice production is still poorly studied. Based on this, we selected two types of irrigation and drainage units (IDUs), which adopted the traditional rice-wheat (RW) rotation pattern and burgeoning RC rotation pattern separately, to investigate the effect of the RC pattern on N runoff loss, inorganic N distribution and N balance of the IDU. The results showed that there was a 241 kg ha-1 yr-1 and 135 kg ha-1 yr-1 N surplus achieved under RW and RC, respectively. Among these, the N surplus of RC was 53 % lower than that of RW during the rice growing season and was 37 % lower at other times. The NH4+-N contents of paddy field soils, rice yields and productive traits were not affected by rotation patterns. Nevertheless, the total nitrogen (TN), dissolved organic nitrogen (DON) and NH4+-N concentrations of RC field water were significantly higher (P < 0.01), and the N runoff losses of the RC pattern increased by 103 % to 855 % compared with the RW pattern. In addition, the NH4+-N reserved in RC ditch sediments substantially increased regardless of the dynamic changes during the rice growing season or from the vertical distribution at depths of 0-40 cm. Our results indicated that the RC pattern was beneficial for decreasing the N surplus without impacting the rice yield. However, larger N runoff losses and more available N flowing into crayfish farming ditches still pose great environmental risks. Therefore, more efficient and cleaner measures should be applied for the N management of IDU under the RC pattern.

Investigating cortico-subcortical circuits during auditory sensory attenuation: A combined magnetoencephalographic and dynamic causal modeling study.

Sensory attenuation refers to the decreased intensity of a sensory percept when a sensation is self-generated compared with when it is externally triggered. However, the underlying brain regions and network interactions that give rise to this phenomenon remain to be determined. To address this issue, we recorded magnetoencephalographic (MEG) data from 35 healthy controls during an auditory task in which pure tones were either elicited through a button press or passively presented. We analyzed the auditory M100 at sensor- and source-level and identified movement-related magnetic fields (MRMFs). Regression analyses were used to further identify brain regions that contributed significantly to sensory attenuation, followed by a dynamic causal modeling (DCM) approach to explore network interactions between generators. Attenuation of the M100 was pronounced in right Heschl's gyrus (HES), superior temporal cortex (ST), thalamus, rolandic operculum (ROL), precuneus and inferior parietal cortex (IPL). Regression analyses showed that right postcentral gyrus (PoCG) and left precentral gyrus (PreCG) predicted M100 sensory attenuation. In addition, DCM results indicated that auditory sensory attenuation involved bi-directional information flow between thalamus, IPL, and auditory cortex. In summary, our data show that sensory attenuation is mediated by bottom-up and top-down information flow in a thalamocortical network, providing support for the role of predictive processing in sensory-motor system.

Effect of irrigation-drainage unit on phosphorus interception in paddy field system.

In lowland agriculture, paddy fields are present in the form of irrigation-drainage unit (IDU), which consists of paddy fields and natural ditches around the fields. Phosphorus (P) export from IDUs significantly impacts water quality in adjacent water bodies. In this study, we explored the characteristics and behavior of P in a typical IDU in Jianghan Plain, China. From 2012 to 2015, we measured P concentrations in different water components of the IDU, i.e., rainwater, irrigation water, field ponding water, runoff water and ditch water, and accounted for spatial and temporal variabilities of the P concentrations. Across the rice growing season, the highest total P (TP) concentration was observed in the field ponding water. Total P concentration in ditch water gradually declined and it reached 0.06 mg L-1 at the rice maturation stage. The concentration was lower than that of incoming irrigation water (0.13 mg L-1) and rainwater (0.17 mg L-1). Although both paddy soil and ditch sediment had low degree of P saturation, the ditch sediment had greater P binding energy (1.58 L mg-1) and larger maximum P sorption (526 mg kg-1) than the soil (0.88 L mg-1 and 455 mg kg-1, respectively). The P mass balance for the rice season over the four consecutive years showed a net depletion of 3.36-8.11 kg P ha-1 yr-1. Overall, IDUs substantially reduced the P concentrations in outputs from the IDUs as compared to inputs through irrigation and rainfall. The IDUs functioned for P retention by extending P settling time and natural degradation of P in the system. Optimizing the IDU management by controlling water discharge during fertilization and disturbance periods can be popularized for its cost saving and environmental benefits.