Evaluation of the nitrification inhibitor (nitrapyrin) application to a soil‐water system for conservation of ammonium released under water logged incubation of soils

Two laboratory incubation experiments were conducted to determine the effect of initial soil water potential on the transformation of urea in large granules to nitrite and nitrate. In the first experiment two soils varying in initial soil water potentials (− 70 and − 140 kPa) were incubated with 2 g urea granules with and without a nitrification inhibitor (dicyandiamide) at 15 °C for 35 d. Only a trace of [Formula: see text] accumulated in a Brookston clay (pH 6.0) during the transformation of urea in 2 g granules. Accumulation of [Formula: see text] was also small (4–6 μg N g−1) in Conestogo silt loam (pH 7.6). Incorporation of dicyandiamide (DCD) into the urea granule at 50 g kg−1 urea significantly reduced the accumulation of [Formula: see text] in this soil. The relative rate of nitrification in the absence of DCD at −140 kPa water potential was 63.5% of that at −70 kPa (average of two soils). DCD reduced the nitrification of urea in 2 g granules by 85% during the 35-d period. In the second experiment a uniform layer of 2 g urea was placed in the center of 20-cm-long cores of Conestogo silt loam with three initial water potentials (−35, −60 and −120 kPa) and the soil was incubated at 15 °C for 45 d. The rate of urea hydrolysis was lowest at −120 kPa and greatest at −35 kPa. Soil pH in the vicinity of the urea layer increased from 7.6 to 9.1 and [Formula: see text] concentration was greater than 3000 μg g−1 soil. There were no significant differences in pH or [Formula: see text] concentration with the three soil water potential treatments at the 10th day of the incubation period. But, in the latter part of the incubation period, pH and [Formula: see text] concentration decreased with increasing soil water potential due to a higher rate of nitrification. Diffusion of various N species including [Formula: see text] was probably greater with the highest water potential treatment. Only small quantities of [Formula: see text] accumulated during nitrification of urea – N. Nitrification of urea increased with increasing water potential. After 35 d of incubation, 19.3, 15.4 and 8.9% of the applied urea had apparently nitrified at −35, −60 and −120 kPa, respectively. Nitrifier activity was completely inhibited in the 0- to 2-cm zone near the urea layer for 35 days. Nitrifier activity increased from an initial level of 8.5 to 73 μg [Formula: see text] in the 3- to 7-cm zone over the 35-d period. Nitrifier activity also increased with increasing soil water potential. Key words: Urea transformation, nitrification, water potential, large granules, nitrifier activity, [Formula: see text] production

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Formation of Organic Iodine Supplied as Iodide in a Soil−Water System in Chiba, Japan

Environmental Science & Technology ◽

10.1021/es1032162 ◽

2011 ◽

Vol 45 (6) ◽

pp. 2086-2092 ◽

Cited By ~ 66

Author(s):

Yoko S. Shimamoto ◽

Yoshio Takahashi ◽

Yasuko Terada

Keyword(s):

Soil Water ◽

Water System ◽

Organic Iodine

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Soil-Related Sustainable Development Goals: Four Concepts to Make Land Degradation Neutrality and Restoration Work

Land ◽

10.3390/land7040133 ◽

2018 ◽

Vol 7 (4) ◽

pp. 133 ◽

Cited By ~ 196

Author(s):

Saskia Keesstra ◽

Gerben Mol ◽

Jan de Leeuw ◽

Joop Okx ◽

Co Molenaar ◽

...

Keyword(s):

Sustainable Development ◽

Soil Water ◽

Systems Thinking ◽

Land Degradation ◽

Sustainable Development Goals ◽

Water System ◽

Paradigm Shifts ◽

Economic Point ◽

Development Goals ◽

Awareness Raising

In the effort to achieve the Sustainable Development Goals (SDGs) related to food, health, water, and climate, an increase in pressure on land is highly likely. To avoid further land degradation and promote land restoration, multifunctional use of land is needed within the boundaries of the soil-water system. In addition, awareness-raising, a change in stakeholders’ attitudes, and a change in economics are essential. The attainment of a balance between the economy, society, and the biosphere calls for a holistic approach. In this paper, we introduce four concepts that we consider to be conducive to realizing LDN in a more integrated way: systems thinking, connectivity, nature-based solutions, and regenerative economics. We illustrate the application of these concepts through three examples in agricultural settings. Systems thinking lies at the base of the three others, stressing feedback loops but also delayed responses. Their simultaneous use will result in more robust solutions, which are sustainable from an environmental, societal, and economic point of view. Solutions also need to take into account the level of scale (global, national, regional, local), stakeholders’ interests and culture, and the availability and boundaries of financial and natural capital. Furthermore, sustainable solutions need to embed short-term management in long-term landscape planning. In conclusion, paradigm shifts are needed. First, it is necessary to move from excessive exploitation in combination with environmental protection, to sustainable use and management of the soil-water system. To accomplish this, new business models in robust economic systems are needed based on environmental systems thinking; an approach that integrates environmental, social, and economic interests. Second, it is necessary to shift from a “system follows function” approach towards a “function follows system” one. Only by making the transition towards integrated solutions based on a socio-economical-ecological systems analysis, using concepts such as nature-based solutions, do we stand a chance to achieve Land Degradation Neutrality by 2030. To make these paradigm shifts, awareness-raising in relation to a different type of governance, economy and landscape and land-use planning and management is needed.

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Arsenic speciation in soil-water system and their uptake by rice (Oryza sativa)

Environmental Arsenic in a Changing World ◽

10.1201/9781351046633-113 ◽

2019 ◽

pp. 289-290

Author(s):

P. Kumarathilaka ◽

J. Bundschuh ◽

S. Seneweera ◽

A.A. Meharg

Keyword(s):

Oryza Sativa ◽

Soil Water ◽

Arsenic Speciation ◽

Water System

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Effect of exopolymeric substances on the kinetics of sorption and desorption of trivalent chromium in soil

Chemical Papers ◽

10.2478/s11696-013-0427-4 ◽

2014 ◽

Vol 68 (1) ◽

Cited By ~ 3

Author(s):

Cetin Kantar ◽

Aydeniz Demir ◽

Nurcan Koleli

Keyword(s):

Soil Water ◽

Water System ◽

Strong Interactions ◽

Column Experiments ◽

Soil Minerals ◽

Total Chromium ◽

Batch Sorption ◽

Exopolymeric Substances ◽

Kinetics Of ◽

Low Solubility

AbstractLaboratory batch sorption-desorption and column experiments were performed to better understand the effects of microbial exopolymeric substances (EPS) on Cr(III) sorption/desorption rates in the soil-water system. The experiments were carried out in two different modes: one mode (sorption) in which Cr(III) and EPS were applied simultaneously, and the other (desorption) included the sequential application of Cr(III) and EPS to the soil-water system. The batch sorption and desorption experiments showed that, while chromium(III) desorption was significantly enhanced in the presence of EPS relative to non-EPS-containing systems, the desorption rates were much smaller than the sorption rates, and the fraction dissolved by EPS accounted for only a small portion of the total chromium initially sorbed onto soil minerals. Similarly, the column experiments suggested that, while the microbial EPS led to an increase in Cr dissolution relative to non-EPS-containing systems, only a small portion of the total chromium initially added to the soil was mobilised. The differences observed in Cr sorption and desorption rates can be explained through the very low solubility and strong interactions of chromium species with soil minerals as well as the mass transfer effects associated with low diffusion rates. The overall results suggest that, while microbial EPS may play an important role in microbial Cr(VI) treatment in sub-surface systems due to the formation of soluble Cr-EPS complexes, the extent and degree of Cr mobilisation are highly dependent on the type of initial Cr sorption.

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