Cadmium phytoavailability evaluation in rice-soil system using a field capacity-derived soil solution extraction: An entire growth period study in subtropical China

Pot experiments were conducted using a sandy loam soil and various electrolyte solutions such as NaCl, CaCl2, Na2SO4, and Hoagland nutrient solution containing all macro- and micro-nutrient elements in appropriate proportions, inducing different electrical conductivity (EC) levels of the soil solution during the growth of Krichauff wheat while the water content in the pot soils was maintained at field capacity. The resulting differences in dry matter production after 40 days of growth clearly indicated the continuous operation of osmotic effect as the EC of the soil solution increased from 0.7 to 41.0 dS/m. However, the osmotic effect became dominant and severely restricted plant growth when the soil solution EC increased above a ‘threshold value’, which was 25 dS/m, corresponding to an osmotic pressure of 900 kPa, in this experiment. Below this EC value, particularly at low EC values, ionic effects due to Na+, Ca2+, SO42–, and Cl– were also evident, but it could not be concluded whether these effects were due to toxicity or ion imbalance. The osmotic effect at EC values above the threshold resulted in greatly reduced water uptake from pot soils, the unused water being in the range 89–96% of the field capacity of the soil. Water use efficiency is a major factor in profitable and sustainable dryland agriculture. Both soil management and selection and breeding of salt-tolerant plants should concentrate on ensuring that the threshold EC value for severe osmotic effects is not reached under field conditions.

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Nitrification of ammonium in different components of a flooded rice soil system

Biology and Fertility of Soils ◽

10.1007/bf00335961 ◽

1996 ◽

Vol 23 (3) ◽

pp. 321-326 ◽

Cited By ~ 15

Author(s):

T. K. Adhya ◽

P. Patnaik ◽

V. R. Rao ◽

N. Sethunathan

Keyword(s):

Rice Soil ◽

Soil System ◽

Flooded Rice ◽

Flooded Rice Soil

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Soil Calcium Status Unrelated to Tipburn of Romaine Lettuce

HortScience ◽

10.21273/hortsci.42.7.1681 ◽

2007 ◽

Vol 42 (7) ◽

pp. 1681-1684 ◽

Cited By ~ 5

Author(s):

Timothy K. Hartz ◽

Paul R. Johnstone ◽

Richard F. Smith ◽

Michael D. Cahn

Keyword(s):

Soil Solution ◽

Calcium Nitrate ◽

Field Capacity ◽

Field Trials ◽

Romaine Lettuce ◽

Soil Calcium ◽

Exchangeable Ca ◽

Salinas Valley ◽

Highly Correlated ◽

A Charge

Application of calcium (Ca) fertilizers is a common practice of California lettuce growers to minimize the occurrence and severity of tipburn, particularly in romaine lettuce (Lactuca sativa L. var. longifolia Lam.). An evaluation of the effect of soil Ca availability on the severity of tipburn in romaine lettuce was conducted in the Salinas Valley of central California in 2005 to 2006. Twenty representative soils from this region were evaluated for Ca availability by ammonium acetate extraction, saturated paste extraction, and extraction of soil solution through centrifugation of soil at field-capacity moisture content. Soil solution Ca in these soils was generally high, ranging from 5 to 80 mmolc·L−1, representing 44% to 71% of cations on a charge basis. Soil solution Ca was highly correlated with saturated paste Ca (r 2 = 0.70) but not with exchangeable Ca (r 2 = 0.01). However, saturated paste extraction significantly underestimated soil solution Ca concentration (regression slope = 0.19). A survey of 15 commercial romaine lettuce fields showed tipburn severity to be unrelated to either leaf Ca concentration or soil Ca availability. The most severe tipburn was observed in fields in which transpiration was reduced by foggy weather during the final 2 weeks of growth. Ca fertilizers (calcium nitrate, calcium thiosulfate, and calcium chloride) applied through drip irrigation during the final weeks of lettuce growth were ineffective in increasing romaine leaf Ca concentration in three field trials; tipburn was present in only one trial, and Ca fertigation had no effect on tipburn severity. We conclude that under typical field conditions in this region, tipburn severity is primarily a function of environmental conditions. Soil Ca availability plays no substantive role in tipburn severity, and Ca fertigation does not improve lettuce Ca uptake or reduce tipburn.

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Effect of Nitrogen Source and Management on Ammonia Volatilization Losses from Flooded Rice-Soil System

Soil Science Society of America Journal ◽

10.2136/sssaj1979.03615995004300020041x ◽

1979 ◽

Vol 43 (2) ◽

pp. NP-NP ◽

Cited By ~ 1

Author(s):

P. L. G. Vlek ◽

E. T. Craswell

Keyword(s):

Nitrogen Source ◽

Ammonia Volatilization ◽

Rice Soil ◽

Soil System ◽

Flooded Rice ◽

Flooded Rice Soil

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Comparing the efficiency of ordinary kriging and cokriging to estimate the Atterberg limits spatially using some soil physical properties

Clay Minerals ◽

10.1180/claymin.2009.044.2.181 ◽

2009 ◽

Vol 44 (2) ◽

pp. 181-193 ◽

Cited By ~ 16

Author(s):

O. Baskan ◽

G. Erpul ◽

O. Dengiz

Keyword(s):

Ordinary Kriging ◽

Mean Squared Error ◽

Field Capacity ◽

Liquid Limit ◽

Atterberg Limits ◽

Engineering Properties ◽

Soil Parameters ◽

Regression Equations ◽

Soil System ◽

The Mean

AbstractThe spatial distribution of the Atterberg limits can be used to distinguish the consistency and behaviour of a soil and its engineering properties, which strongly depends on the water content of the soil and types of silts and clays in the soil. By spatial modeling, and comparing the results of ordinary kriging with the cokriging approach, this study aims to find correlations between the Atterberg limits and the selected physical soil parameters in order to examine how effective they are in generating an understanding of the dynamics of a physical soil system.In 156 soil samples, the Atterberg limits and soil moisture conditions were determined, and auxiliary functions were selected by application of cokriging using correlation analysis and regression equations obtained by the residual maximum likelihood (REML). These techniques were evaluated by the results of the mean absolute error (MAE) and the mean squared error (MSE). Cokriging analysis was found to be more effective at estimating the liquid limit (WLL) and the plastic limit (WPL) than kriging analysis and with smaller error values. On the other hand, the kriging approach, which had smaller MAE and MSE values, was more effective at estimating the plasticity index (WPI) values than the cokriging method. Unlike the REML regression equations, the field capacity (FC) value was the more suitable parameter for the cokriging estimates. When the necessary labour and time were considered for determining the Atterberg limits, both kriging and cokriging were found to be applicable for estimation of these limits.

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