Effect of fertilization on soil phosphorus in a long-term field experiment in southern Finland

Abstract

A field experiment was established in 1978 on a loam soil (pH in CaCl2 7.1) to monitor gradual changes in the soil P status as response to different P fertilization regimes. For 18 years, cereals or grass were cultivated without P fertilization (P0) or with annual P application of 35 kg ha-1 (P1) or 70-79 kg P ha-1 and 71-83 kg K ha-1 (P2K). The effects of the treatments on the crop yield varied yearly. The Chang and Jackson fractionation analysis revealed that fertilizer P not taken up by the plant crops was mostly in the NH4F extract and to a lesser extent in the NaOH extract. The NH4F-extractable P proved also to be the main P source for plants. However, the changes in the reserves of inorganic and organic P did not agree very well with the calculated P balance in soil (applied P minus plant P uptake). This disproportion was partly explained by the soil movement from plots to the neighbouring ones during the experiment. Phosphorus extractable in acid ammonium acetate or water decreased gradually when no P was applied and increased with increasing P accumulation. The changes in the inorganic P reserves due to different P fertilization history were reflected a little more sensitively in the water extraction test than in the acid acetate test.

Phosphorus status of diverse soils in Finland as influenced by long-term P fertilisation 2.Changes of soil test values in relation to P balance with references to incorporation depth of residual and freshly applied P

“…The analytical recovery of applied P was higher between the medium rates of P, 15 and 45 kg ha -1 , on average 65%. This is comparable to other studies (Yli-Halla 1989, Jaakkola et al 1997) and can be considered as a reasonably high recovery (4) OSPM ( Fig. 1.…”

“…The exchange of topsoil between adjacent plots caused by annual tillage could have affected the spatial distribution of P in the soil markedly during the last experimental years (Jaakkola et al 1997, Sibbesen et al 2000. Recent soil tests for a clay soil in Mietoinen suggest that soil mixing may occur more rapidly than estimated previously.…”

Does balanced phosphorus fertilisation sustain high herbage yields and phosphorus contents in alternately grazed and mown pastures?

“…Similar linear relations between cumulative P surpluses and soil P values were found in other multiple year experiments on grazed and mown grasslands although different soil P tests were used c Fig. 3 Mean P-AL-values of the topsoil (0-5 cm; left-hand side; and 5-10 cm; right-hand side) at the four sites (sand1, sand2, clay, peat), as function of phosphorus surpluses in kg P ha -1 (P0, P9 and P18), averaged over two levels of nitrogen input, during the period 1997-2011 (Jaakkola et al 1997;Messiga et al 2015;Robertson and Nash 2008). The change of fertiliser type on sand1 from high to low water soluble P did not change the relation between P surplus and P-AL-value.…”

Effects of repeated phosphorus fertilisation on field crops in Finland 2.Sufficient phosphorus application rates on silty and sandy soils

“…On the clay loam soil 9 at the more sloping site, the rainy season of 1981 was favourable for the supply of P to oats, in the same way as on a loam soil studied by Jaakkola et al (1997). Another good performance of crop with the control treatment was found in the winter rye grown on soil 9 in 1990-1991, when the weather conditions were obviously favourable for root growth and nutrient absorption.…”