Stratification of soil phosphorus, pH, and macro-cations under intensively cropped grass ley

Abstract

The large amounts of nutrients applied to and removed from soil by intensive grass production may cause quick changes in the nutrient pools available to plants and exposed to leaching and runoff losses. Stratification of applied nutrients is especially important for phosphorus (P), which moves slowly in soil. To study the vertical distribution of extractable nutrients and soil pH in different types of ley soil, P fertilisers were incorporated or placed prior to sowing or broadcast annually at ten sites for 3 years. Then the soils were sampled in several layers 2.5 or 5 cm deep and analysed for pH and the concentrations of phosphorus, potassium (K), calcium (Ca), and magnesium (Mg) extractable with acid ammonium acetate. In mineral soils, broadcast P mainly remained within the uppermost 2.5 cm of soil, in which the concentrations of extractable P more than doubled during the study period. When commonly used NK and NPK fertilisers were applied, the uppermost 5 cm of soil was acidified by about 0.5 pH units and its Ca value decreased by about 25%. Broadcast K enriched a thin surface layer even if the K balance was negative. Estimation of the concentration of dissolved phosphate in runoff suggested that the high P losses that are possible at excessive levels of soil test P can be diminished by perennial grasses supplied with abundant water and other nutrients. Surface-applied P appeared to increase the losses, but even a shallow placement seemed to prevent them efficiently if all fertiliser granules become covered with soil.

The flows and balances of P, K, Ca and Mg on intensively managed Boreal high input grass and low input grass-clover pastures

“…The removal of P in milk (58%) is comparable with Whitehead (2000), who estimated that milk accounted for 67% of the total P output from intensively managed dairy pasture. The total amount of P output and yearly P excess for the G treatment were nearly equal to that of silage production (Saarela and Vuorinen 2010). In Central Finland's light mineral soils most of the P losses occur during snowmelt, and are transported in surface runoff (Turtola and Kemppainen 1998) when cations are lost preferentially by leaching through the soil matrix whenever the soil moisture exceeds field capacity (Owens et al 2003).…”

“…The amount of fertilizer P (applied according to Finnish fertilization recommendations) of 23 kg P ha -1 increased the soil ammonium acetate soluble P concentration only 4.7 mg l -1 y -1 . The rest of the fertilizer P was probably used by plants or adsorbed on short-range-order oxides and Al and Fe oxides, common in weakly developed acidic Finnish soils (Peltovuori 2006, Saarela andVuorinen 2010). In the GC treatment the surface soil P concentration remained low throughout the experiment.…”

Pronounced surface stratification of soil phosphorus, potassium and sulfur under pastures upstream of a eutrophic wetland and estuarine system

“…The positive correlation between PBI and total P concentration at the beef farm resulted from some individual profiles having a higher PBI throughout the profile and hence enabling greater amounts of extractable P to be tightly bound. However, the very high extractable P concentrations in the soil surface layers indicates that this binding capacity had been saturated and that, consequently, P had accumulated as extractable P. Overall, the high concentrations of P and other nutrients at the soil surface likely result from the continuous input to the soil surface of plant material and animal dung (for P) and urine (for K) (Haynes and Williams 1992), as well as fertiliser (Haynes and Williams 1992;Saarela and Vuorinen 2010;McLaren et al 2015McLaren et al , 2016. Maintenance/increase of these high surface concentrations is also exacerbated by continuous cycling of P between aboveground and belowground pools as illustrated by the strong positive linear relationship between total P concentration in the litter and extractable P concentration in the top 10 mm of soil.…”

“…1). The study builds upon previous studies of nutrient stratification in pastures and crops (McLaughlin et al 1990;Haynes and Williams 1992;Cayley et al 2002;Dougherty et al 2006;Vu et al 2009;Saarela and Vuorinen 2010;Haygarth et al 1998) by including, in a single study, three sampling times within the growing season, small (10 mm) soil depth increments and measurements of extractable potassium and sulfur, pH and soil organic matter in addition to extractable and total P. The paddocks were under commercial management during the study.…”

Sisävesien fosforikuormitus Kirmanjärven valuma-alueella Pohjois-Savossa

“…2006. Nurmien viljely muokkaamatta kerryttää fosforia maan pintakerrokseen (Saarela & Vuorinen 2009), mikä johtuu etenkin nurmivuosina pintaan annetusta fosforilannoituksesta ja pintaan levitettävästä lietelannasta. Pintamaan korkean fosforitason on osoitettu lisäävän valumaveden fosforipitoisuutta (Sharpley 1995, Turtola & Yli-Halla 1999, ja siten kasvattavan kuormituspotentiaalia.…”