Changes in the soil phosphorus status of agricultural land in the Netherlands during the 20th century J. A. Reijneveld 1 , P. A. I. E hlert 2 , A. J. T ermorshuizen 1 & O. O enema 2 1 BLGG AgroXpertus, PO Box 115, NL-6860 AC Oosterbeek, The Netherlands, and 2 Wageningen University & Research Centre, Alterra, PO Box 47, NL-6700 AA Wageningen, The Netherlands Abstract The Netherlands has a high cumulative mean phosphorus (P) balance. In the 20th century, cumulative mean P surpluses were ca. 4500 kg P 2 O 5 ⁄ ha. The annual surpluses have levelled off because of manure application limits from 1984 onwards. We report the effect of soil type, land use, and manure policy on changes in soil P of fields in the Netherlands during the 20th century. We used data (>5 million soil P tests) from the soil analysis laboratory BLGG AgroXpertus. Our results show that soil P has increased on average to fairly high and high ratings. Differences between regions and between land use have remained high from the first records in the 1930s; on arable land the increase continued until the end of our study period while on grassland no changes are evident in the last decades. In general regions with high livestock density have high soil P status. Soil P increased in the order bulbfields < grassland < arable land < maize land < horticulture, and in the order loess < clay < peat < sand soils. Spatial variations in P values reflect more the market value of the crops and regional availability of animal manure than (fertilizer) recommendations. Manure policy since 1984 has resulted in increasingly tight restrictions on P application from manure and fertilizers, but the effects are not yet clearly reflected in changed trends in soil P. Keywords: Soil-test database, soil phosphorus, the Netherlands, soil fertility, changes, land use Introduction Uptake of P by plants is very sensitive to its concentration in the soil solution (e.g., Barber, 1982; Marschner, 1985; Holford, 1997). This concentration is low, but is buffered by various P fractions in the solid phase through complex desorption–adsorption, dissolution–precipitation and mineralization–immobilization processes (Nye & Tinker, 1977; Ehlert et al., 2003; Van Rotterdam-Los, 2010). These processes are in turn influenced by the presence and activity of plant roots and environmental conditions. Assessing the availability of P to plants has been a key question in soil fertility research for more than a century (Daubeny, 1845; Dyer, 1894; Anderson, 1960; Sissingh, 1961; Kamprath & Watson, 1980; Sibbesen, 1983; Sims, 1998). Various extractants have been used to determine P availability to crops. Extracted soil P has been related to crop yield response to P fertilizer application as observed in field experiments leading to calibrated P fertilizer recommendations (Sibbesen, 1983; Neyroud & Lischer, 2003). These experiments and analyses form the basis for recommending economically optimal application rates. These recommendations have significantly contributed to alleviating P deficiency in crop production and also to optimizing the agronomic efficiency of P management (Van der Paauw, 1971; Sims et al., 2000). A low soil P status is improved to ample sufficiency through P application while a high soil P status will decrease to adequate sufficiency through limited application. However, these recommendations seem less effective in preventing supra-optimal P applications as the extent of agricultural land with soil P status above the recommended ranges has become significant in many countries. For example, it has been reported that 50% of all arable fields in Sweden have a soil P status corresponding to high or very high (Eriksson et al., 1997 in Djodjic et al., 2004). In Belgium about 80% of the arable lands and 60% of grasslands are considered fairly high to very high in soil P (BDB, 2005). In New York State 47% of the tested soil samples were higher than the recommended ranges (Ketterings et al., 2005). Excessive enrichment of soils with P increases the risk of losses to the aquatic environment through erosion, overland flow and subsurface leaching (Pautler & Sims, 2000; Sims Correspondence: J. A. Reijneveld. E-mail: arjan.reijneveld@blgg.nl Received June 2010; accepted after revision June 2010 Soil Use and Management, December 2010, 26, 399–411 doi: 10.1111/j.1475-2743.2010.00290.x ª 2010 The Authors. Journal compilation ª 2010 British Society of Soil Science 399 Soil Use and Management