Charge characteristics of soil in a lowland tropical moist forest in Panama in response to dry-season irrigation

Soil Research ◽  
2002 ◽  
Vol 40 (2) ◽  
pp. 269 ◽  
Author(s):  
Joseph B. Yavitt ◽  
S. Joseph Wright
Keyword(s):  
Surface Charge ◽  
Surface Soil ◽  
Soil Nutrient ◽  
Soil Surface ◽  
Nutrient Status ◽  
Dry Season ◽  
Soil Nutrient Status ◽  
Variable Charge ◽  
Subsurface Soil ◽  
Moist Forest

Although the hot, moist tropics in the Republic of Panama receive more than 2000 mm of rain per year, soils dry considerably during the 4-month dry season. We examined the effect of seasonal drought by irrigating two 2.25-ha plots of lowland tropical moist forest on Barro Colorado Island (BCI) for 5 consecutive dry seasons. Irrigation decreased soil permeability and improved soil nutrient status, which prompted this study of soil charge characteristics in the irrigated and control plots. Soil was an Alfisol, and thus it was not clear a prioriwhether variable-charge or permanent-charge components dominated. Surface soil (0–15 cm) had a pH(H2O) of 5.5 and pH(KCl) of 4.8. Subsurface soil (30–45 cm) had a pH(H2O) of 4.8 and a pH(KCl) of 3.5. The point of zero salt effect (PZSE), measured by titration, varied from 3.7 to 5.0 in surface soil and from 3.5 to 4.2 in subsurface soil. Variable charge of surface soil was 2.6 cmolc/kg.pH unit after the dry season in April versus 3.2 cmolc/kg.pH unit after the wet season in December in both control and dry-season irrigated plots, reflecting seasonal differences in pH and PZSE. The point of zero net charge (PZNC), measured by ion retention, was at pH <2.0, indicating that permanent-charge components dominated the soil surface charge. Five years of dry-season irrigation resulted in pH(H2O) increasing by 0.6 units and pH(KCl) increasing by 0.2 units. As well, irrigation increased the amount of permanent charge and cation retention, leading to less sorption of phosphate and sulfate. The results have important ecological implications, showing mechanistically how wetter conditions affected soil surface charge leading to improved soil nutrient status. permanent charge, soil pH, tropical forest soil, variable charge, water regime.

Vegetation Cover Classes and Soil Nutrient Status of the Mulga Lands of South-West Queensland.

1992 ◽  
Vol 14 (1) ◽  
pp. 40 ◽  
Author(s):  
DE Baker ◽  
RL Miles ◽  
VJ Eldershaw
Keyword(s):  
Surface Soil ◽  
Critical Role ◽  
Soil Nutrient ◽  
Nutrient Status ◽  
Phosphorus Level ◽  
Soil Nutrient Status ◽  
South West ◽  
Conductivity Profile ◽  
Nutrient Changes ◽  
Semi Arid

The soils of the semi-arid mulga lands of south-west Queensland are subject to degradation from both erosion and woody weeds. Limited quantification of the nutrient changes in the red earths under these forms of degradation indicates that eroded land has a lower phosphorus level in the surface soil, a lower pH at depth and an inverse electrical conductivity profile, compared with land vegetated by mulga or grassland. Land invaded by turkey bush did not differ in nutrient characteristics from mulga or grassland. It is concluded that phosphorus will play a critical role in any regeneration programme for eroded land.

Combining sub-field scale soil sampling and GIS interpolation techniques for mapping nutrient hotspots 

2021 ◽  
Author(s):  
Emma Hayes ◽  
Suzanne Higgins ◽  
Donal Mullan ◽  
Josie Geris
Keyword(s):  
Water Quality ◽  
Soil Nutrient ◽  
Nutrient Status ◽  
Soil Sampling ◽  
Nutrient Losses ◽  
Field Scale ◽  
Soil Nutrient Status ◽  
Interpolation Techniques ◽  
Nutrient Hotspots ◽  
Field Variability

<p>The EU Water Framework Directive (WFD) aims to target prevalent poor water quality status. Of the various contributing sources agriculture is particularly important due to the high loading rates of sediment and nutrient losses associated with fertilisation, sowing, and cropping regimes. Understanding soil nutrient status and the potential pathways for nutrient loss either through point or diffuse sources is an important step to improve water quality from an agricultural perspective. Research has demonstrated extensive in-field variability in soil nutrient status. A sampling regime that explores this variability at a sub-field scale is necessary. Traditional soil sampling consists of taking 20-30 cores per field in a W-shaped formation to produce a single bulked core, however, it generally fails to locate nutrient hotspots at finer resolutions. Inappropriate generalised fertilisation and management recommendations can be made in which nutrient hotspots or deficient zones are overlooked. Gridded soil sampling can reveal the full degree of in-field variability in nutrient status to inform more precise and site-specific nutrient applications. High soil phosphorus levels and the concept of legacy nutrient accumulation due to long-term over-application of phosphorus fertiliser in addition to animal slurry is a problem across the island of Ireland.</p><p>This research aims to locate and quantify the presence of soil nutrient hotspots at several field-scale locations in the cross-border Blackwater catchment in Northern Ireland / Republic of Ireland. Based on 35 m sampling grids, the nutrient content at unsampled locations in each field was determined using GIS interpolation techniques. Particular attention was paid to phosphorus, given its role in eutrophication. Gridded soil sampling enables the identification of nutrient hotspots within fields and when combined with an analysis of their location in relation to in-field landscape characteristics and knowledge of current management regimes, the risk of nutrient or sediment loss potential may be defined. This research concluded that traditional W soil sampling of producing one average value per field is not appropriate to uncover the degree of spatial variability in nutrient status and is inappropriate for catchment management of agricultural systems for controlling nutrient losses. Soil sampling at multiple locations per field is deemed to be cost-prohibitive for many farmers. However, sub-field scale soil sampling and appropriate geostatistical interpolation techniques can reveal the degree of variability and suggest an appropriate resolution for field-scale nutrient management that may be necessary to achieve measurable improvements in water quality.</p>

scholarly journals Soil Nutrient Status of Brahmaputra Floodplain Area in Tangail Sadar Upazila for Agricultural Uses

2016 ◽  
Vol 8 (2) ◽  
pp. 11-14
Author(s):  
MAM Hossen ◽  
SA Lira ◽  
MY Mia ◽  
AKMM Rahman
Keyword(s):  
Soil Nutrient ◽  
Nutrient Status ◽  
Available Phosphorus ◽  
Soil Nutrient Status ◽  
Fe Content ◽  
P Content ◽  
Zn Content ◽  
Floodplain Area ◽  
Very High ◽  
Brahmaputra Floodplain

Soil samples from high land, medium high land, medium low land and low land of Brahmaputra Floodplain area showed that pH of the soils were slightly acidic; organic matter (OM) content was medium; total nitrogen (N), available potassium (K) and boron (B) content were low; available phosphorus (P) content was very low; available sulfur (S) and calcium (Ca) content were medium to very high; magnesium (Mg) and zinc (Zn) content were low to optimum; copper (Cu), manganese (Mn) and iron (Fe) content were very high suggesting the fact that soils of this area is moderately suitable for agricultural uses.J. Environ. Sci. & Natural Resources, 8(2): 11-14 2015

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