Speciation of phosphorus in a fertilized, reduced-till soil system: in-field treatment incubation study

Citation: Khatiwada, Raju, Ganga M. Hettiarachchi, David B. Mengel, and Mingwei Fei. “Speciation of Phosphorus in a Fertilized, Reduced-Till Soil System: In-Field Treatment Incubation Study.” Soil Science Society of America Journal 76, no. 6 (2012): 2006–18. https://doi.org/10.2136/sssaj2011.0299.Phosphorus management in reduced-tillage systems is a great concern for farmers. Conclusive positive results of deep-banding P fertilizers compared with broadcast application and the chemistry of reduced-tillage systems remain unclear. Knowledge of the dominant solid P species present in soil following application of P fertilizers and the resulting potential P availability would help us understand and efficiently manage P in reduced-tillage systems. The objective of this research was to study the influence of placement (broadcast vs. deep-band P), fertilizer source (granular vs. liquid P), and time on the reaction products of P under field conditions. Changes in soil pH, resin-extractable P, total P, and speciation of P were determined at different distances from the point of fertilizer application at 5 wk and 6 mo after P application at a rate of 75 kg ha−1 to a soil system that was under long-term reduced tillage. Resin-extractable P was lower for broadcast treatments compared with deep-band treatments for both time periods. Resin-extractable P was greater in the liquid P-treated soils than in the granular P-treated soils. Speciation results showed that granular P fertilizers tended to form Fe–P-like forms, whereas liquid forms remained in adsorbed P-like forms in the soil 5 wk after application; moreover, speciation results showed granular P fertilizers precipitated less when deep-banded. During the 6-mo period following application, reaction products of broadcast granular, broadcast liquid, and deep-band granular fertilizers transformed to Ca-phosphate or mixtures of Ca-, Fe- and adsorbed-phosphate-like forms, whereas deep-band liquid P remained as mainly adsorbed P-like forms. Deep-banding of P would most likely provide a solution that is both agronomically and environmentally efficient for reduced-till farmers

Evidence for Holocene Aeolian Activity at the Close of the Middle Bronze Age in the Eastern Carpathian Basin: Geoarchaeological Results from the Mureş River Valley, Romania

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96325/1/gea21434.pd

Soil Organic Carbon Pools in Riparian Landscapes of Southern New England

Riparian zones are important catchment-scale depositional environments that receive episodic influx of sediment and C from watershed sources. The specific impacts of upland disturbances on riparian soil development and soil organic carbon (SOC) dynamics are still largely unknown. The goal of our study was to understand the role of riparian soils in retaining C at the landscape and catchment scales. We quantified SOC pools to a depth of 1 m at 29 headwater riparian sites in southern New England. Riparian SOC pools ranged from 117 to 495 Mg C ha-1, with a mean pool of 246 Mg C ha-1. On average, \u3e50% of the total SOC was stored below 30 cm. Riparian SOC pools differed significantly between soils formed in relatively fast accreting environments (those that contain buried surface horizons; 277 Mg C ha -1) and those in slow accreting environments where buried horizons were absent (188 Mg C ha-1). Catchment-scale analysis of SOC distribution indicated that riparian zones, on average, occupy 8% of the total watershed area yet store as much as 20% of the total catchment SOC. These results suggest that even though riparian zones occupy a small percentage of the overall watershed, these areas are an important component of the landscape for storage of SOC deposited as a result of catchment-scale disturbances