Evidence for a uniformly small isotope effect of nitrogen leaching loss: results from disturbed ecosystems in seasonally dry climates

The use of water-saving irrigation techniques has been encouraged in rice fields in response to irrigation water scarcity. Straw return is an important means of straw reuse. However, the environmental impact of this technology, e.g., nitrogen leaching loss, must be further explored. A two-year (2017–2018) experiment was conducted to investigate the vertical migration and leaching of nitrogen in paddy fields under water-saving and straw return conditions. Treatments included traditional flood irrigation (FI) and two water-saving irrigation regimes: rain-catching and controlled irrigation (RC-CI) and drought planting with straw mulching (DP-SM). RC-CI and DP-SM both significantly decreased the irrigation input compared with FI. RC-CI increased the rice yield by 8.23%~12.26%, while DP-SM decreased it by 8.98%~15.24% compared with FI. NH4+-N was the main form of the nitrogen leaching loss in percolation water, occupying 49.06%~50.97% of TN leaching losses. The NH4+-N and TN concentration showed a decreasing trend from top to bottom in soil water of 0~54 cm depth, while the concentration of NO3−-N presented the opposite behavior. The TN and NH4+-N concentrations in percolation water of RC-CI during most of the rice growth stage were the highest among treatments in both years, and DP-SM showed a trend of decreasing TN and NH4+-N concentrations. The NO3−-N concentrations in percolation water showed a regular pattern of DP-SM > RC-CI > FI during most of the rice growth stage. RC-CI and DP-SM remarkably reduced the amount of N leaching losses compared to FI as a result of the significant decrease of percolation water volumes. The tillering and jointing-booting stages were the two critical periods of N leaching (accounted for 74.85%~86.26% of N leaching losses). Great promotion potential of RC-CI and DP-SM exists in the lower reaches of the Yangtze River, China, and DP-SM needs to be further optimized.

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Biochar mitigates dissolved organic carbon loss but does not affect dissolved organic nitrogen leaching loss caused by nitrogen deposition in Moso bamboo plantations

Global Ecology and Conservation ◽

10.1016/j.gecco.2018.e00494 ◽

2018 ◽

Vol 16 ◽

pp. e00494

Author(s):

Zhaofeng Lei ◽

Quan Li ◽

Xinzhang Song ◽

Weifeng Wang ◽

Zhiting Zhang ◽

...

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Nitrogen Deposition ◽

Dissolved Organic Nitrogen ◽

Organic Nitrogen ◽

Nitrogen Leaching ◽

Moso Bamboo ◽

Carbon Loss ◽

Leaching Loss

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Geography of Iridaceae in Africa

Bothalia ◽

10.4102/abc.v14i3/4.1208 ◽

1983 ◽

Vol 14 (3/4) ◽

pp. 559-564 ◽

Cited By ~ 2

Author(s):

P. Goldblatt

Keyword(s):

Cape Floristic Region ◽

Sub Saharan Africa ◽

Tropical Africa ◽

Winter Rainfall ◽

Seasonally Dry ◽

Worldwide Distribution ◽

The Family ◽

Sub Saharan ◽

Dry Climates ◽

Eastern Half

Iridaceae, a family of worldwide distribution, comprises some 1 500 species and 85 genera. It exhibits its greatest radiation in Sub-Saharan Africa, where over half the species and some 48 genera occur. 45 of which are endemic. All three major subfamilial taxa are represented in Africa, where Ixioideae are almost entirely restricted, with extensions into Eurasia. Areas of greatest concentration are either montane or in areas of winter rainfall. In southern Africa alone, there are some 850 species in 46 genera, making the family the fifth largest in the flora. In the Cape Floristic Region there are 620 species, and the family is the fourth largest in this area. All major infrafamilial groups occur in the Cape Region where most of the variability as well as generic radiation is encountered. The idea of a southern origin for Iridaceae in Africa is analysed systematically, and is correlated with the major climatic changes that occurred in Africa since the mid-Tertiary, and culminated in the seasonally dry climates along the west coast. The establishment of mediterranean climate in the southwest provided the stimulus for massive speciation and radiation of the family there. Plio-Pleistocene uplift along the eastern half of the African continent led to the establishment of substantial upland areas and allowed the spread of some genera, such as Romulea, Gladiolus, Moraea, and Hesperantha into tropical Africa. Short-distance dispersal probably accounts for the presence of genera such as Gladiolus, Gynandriris and Romulea in Eurasia.

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Middle Miocene through Pliocene North American Vegetational History: 16.3-1.6 Ma

Late Cretaceous and Cenozoic History of North American Vegetation (North of Mexico) ◽

10.1093/oso/9780195113426.003.0010 ◽

1999 ◽

Author(s):

Alan Graham

Keyword(s):

North America ◽

Sierra Nevada ◽

North American ◽

Middle Miocene ◽

Middle Eocene ◽

Alaska Range ◽

Seasonally Dry ◽

Middle Latitudes ◽

The North ◽

Dry Climates

During the Middle Miocene through the Pliocene the Appalachian Mountains underwent continued erosion and approached modern elevations. The Rocky Mountains had undergone uplift to half or more of their present elevation during the Late Cretaceous to Middle Eocene Laramide Revolution; after a lull during the Middle Eocene through the Early Miocene, there was increased tectonic activity beginning ~12 Ma and especially between 7 and 4 Ma. Locally some highlands may have approached or attained modern elevations. The increasingly high mountains and plateaus of Asia and North America deflected the major air streams southward, bringing colder polar air into the middle latitudes of North America. An extensive Antarctic ice sheet further cooled ocean waters and contributed to the spread of seasonally dry climates. The elimination of most of the Asian exotics from the North American flora dates to the Late Miocene-Pliocene as a result of a decline in summer rainfall. The Sierra Nevada attained about two-thirds of their present elevation within the past 10 Ma. They were appreciably elevated at ~5 Ma, stood at ~2100 m at 3 Ma, and have risen ~950 m since 3 Ma (Huber, 1981). The California Coast Ranges and Cascade Mountains attained significant heights by 3 Ma, and there was a rapid rise of the Alaska Range at ~6 Ma. Temperatures increased between ~18 and 16 Ma. In the absence of major plate reorganization and intense volcanic activity and with increased erosion from continued replacement of the dense evergreen forest by deciduous forest and shrubland (increasing albedo), atmospheric CO2 concentration decreased and a sharp lowering of temperature occurred in the Middle Miocene between 15 and 10 Ma. Eolian dust deposits increased in the Late Cenozoic, suggesting greater aridity (Rea et al., 1985). This is supported by kaolinite records from North Atlantic deep sea sediments (Chamley, 1979). At ~4.8~4.9 Ma global cooling and a marine regression of ~40~50 m combined to isolate the Mediterranean Basin from the ocean and to concentrate large volumes of salt as water evaporated. The biota was destroyed, giving rise to the term Messinian salinity crisis.

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Effects of Biochar Addition on Nitrogen Leaching Loss in the Vegetable Soil

Journal of Advanced Agricultural Technologies ◽

10.18178/joaat.6.2.83-90 ◽

2019 ◽

Vol 6 (2) ◽

pp. 83-90

Author(s):

Yingliang Yu ◽

◽

Linzhang Yang ◽

Lihong Xue

Keyword(s):

Nitrogen Leaching ◽

Leaching Loss ◽

Vegetable Soil

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Nitrogen Leaching Loss Estimation from Paddy Soil in the Taihu Lake Region of China by a Newly Developed Simple Model

Journal of Agronomy Research ◽

10.14302/issn.2639-3166.jar-19-3097 ◽

2019 ◽

Vol 2 (3) ◽

pp. 19-30

Author(s):

Wen-Ming Xie ◽

You Ma ◽

Shi-Jun Li ◽

Wei-Ming Sh ◽

...

Keyword(s):

Paddy Soil ◽

Taihu Lake ◽

Agricultural Land ◽

Surface Water Quality ◽

Exponential Model ◽

Nitrogen Leaching ◽

Loss Estimation ◽

N Leaching ◽

Leaching Loss ◽

Lake Region

Nitrogen leaching as a direct pathway of N loss from agricultural land can negatively affect groundwater and surface water quality. However, a simple and efficient method for nitrogen leaching loss estimation is still inefficient. In this study, an exponential model was developed using the experimental data from a two-year field experiment conducted in the Taihu Lake region of China to simulate the N leaching from the paddy soil. The results showed the leached N was in the range of 5.66 to 8.45 kg N/ha during the whole rice season, which was accounted for 1.7%-2.1% of the applied N. A good agreement between the measured and model predicted results for N leaching loss was observed, suggesting the validity of the established model. The model was further validated with the data of other studies in other regions. The results demonstrated this model is able to simulate the N leaching loss accurately and can provide a beneficial tool for users to predict N leaching loss in paddy soil.

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Behavioural divergence during biological invasions: a study of cane toads ( Rhinella marina ) from contrasting environments in Hawai'i

Royal Society Open Science ◽

10.1098/rsos.180197 ◽

2018 ◽

Vol 5 (4) ◽

pp. 180197 ◽

Cited By ~ 3

Author(s):

Jodie Gruber ◽

Gregory Brown ◽

Martin J. Whiting ◽

Richard Shine

Keyword(s):

Range Expansion ◽

Ecological Factors ◽

Seasonally Dry ◽

Range Edge ◽

Spatial Sorting ◽

Exploration Risk ◽

Per Se ◽

Dry Climates ◽

Range Core ◽

Expanding Population

Invasive species must deal with novel challenges, both from the alien environment and from pressures arising from range expansion per se (e.g. spatial sorting). Those conditions can create geographical variation in behaviour across the invaded range, as has been documented across regions of Australia invaded by cane toads; range-edge toads are more exploratory and willing to take risks than are conspecifics from the range-core. That behavioural divergence might be a response to range expansion and invasion per se , or to the different environments encountered. Climate differs across the cane toads' invasion range from the wet tropics of Queensland to the seasonally dry climates of northwestern Western Australia. The different thermal and hydric regimes may affect behavioural traits via phenotypic plasticity or through natural selection. We cannot tease apart the effects of range expansion versus climate in an expanding population but can do so in a site where the colonizing species was simultaneously released in all suitable areas, thus removing any subsequent phase of range expansion. Cane toads were introduced to Hawai'i in 1932; and thence to Australia in 1935. Toads were released in all major sugarcane-growing areas in Hawai'i within a 12-month period. Hence, Hawai'ian cane toads provide an opportunity to examine geographical divergence in behavioural traits in a climatically diverse region (each island has both wet and dry sides) in the absence of range expansion subsequent to release. We conducted laboratory-based behavioural trials testing exploration, risk-taking and response to novelty using field-caught toads from the wet and dry sides of two Hawai'ian islands (Oahu and Hawai'i). Toads from the dry side of Oahu had a higher propensity to take risks than did toads from the dry side of Hawai'i. Toads from Oahu were also more exploratory than were conspecifics from the island of Hawai'i. However, toads from wet versus dry climates were similar in all behaviours that we scored, suggesting that founder effects, genetic drift, or developmentally plastic responses to ecological factors other than climate may have driven behavioural divergence between islands.

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