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Soil amendments, such as straw mulch, organic fertilizers and superabsorbent polymer (SAP), are extensively applied to improve soil structure and porosity, and we reported the functional consequences of the individual application of these amendments in our previous study. However, whether combined amendments are more effective than their individual applications for improving soil pore structure is unknown. Here, we conducted X-ray computed tomography (CT) scanning on undisturbed soil columns to investigate the efficiency of two-amendment application, including straw mulch and organic manure, SAP and organic manure, or SAP and straw mulch, for improving soil pore properties and pore distribution. The X-ray CT technique allows us to accurately determine the number, morphology, and location of macropores (>1 mm in diameter) and smaller pores (0.13–1.0 mm). Compared to the control treatment, which showed the lowest increase in soil porosity, all the combined treatments led to an increase in the numbers of both macropores and smaller soil pores, causing a significant improvement in soil structure and porosity. Among these treatments, the application of both straw mulch and organic manure was the most effective for improving soil porosity and soil physical structure.

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. This content downloaded from 130.102.42.98 on Mon, SUMMARY(1) Bulinus globosus populations were sampled weekly in two reservoirs over 2 years, using plastic sheet snail traps and mark recapture techniques to measure density, growth rates and reproduction.(2) Captive cohorts were raised in netted boxes in the reservoirs to measure age specific reproduction and egg viability.(3) Growth rates were used to identify snail cohorts, and life tables were constructed to measure mortality rates and the intrinsic rate of natural increase (rm).(4) Values for ri were inversely related to mean water temperatures, with no positive values when the mean water temperature exceeded 28-5 'C during a cohort's early reproductive phase.(5) Rainfall (and associated environmental variables) appear to influence the carrying capacity of the snail habitat, so that in both reservoirs, populations increased fastest and to the highest densities when large amounts of unseasonal rain fell during the coolest months.

Pod shattering resistance index (SRI) is a key factor affecting the mechanical harvesting of rapeseed. Research on the differences in pod shattering resistance levels of various rapeseed varieties can provide a theoretical basis for varietal breeding and application in mechanical harvesting. The indicators on pod shattering resistance including pod morphology and wall components were evaluated on eight hybrids and open pollinators, respectively, during 2012–2014. The results showed the following: (1) From the current study, SRI varied greatly with variety, and conventional varieties had stronger resistance than hybrid according to the physiological indexes. and (2) Under the experimental conditions, the SRI was linearly related to pod wall weight and the water content in pod walls, and the goodness-of-fit measurements for the regression model of the SRI based on pod wall weight and water content were 0.584** and 0.377*, respectively, reaching the significant level. This illustrated that pod wall weight and the water content in pod walls determined the SRI. (3) Compared with the relative contents of biochemical components in pod walls, the contents of particular biochemical components in pod walls had closer correlations with SRI. Among the biochemical components, the hemicellulose content was the decisive factor for the SRI.