Phosphorus concentrations in subsurface water as influenced by cropping systems and fertilizer sources

Abstract

Carefoot, J. P. and Whalen, J. K. 2003. Phosphorus concentrations in subsurface water as influenced by cropping systems and fertilizer sources. Can. J. Soil Sci. 83: 203-212. Over-fertilization of agricultural soils with P has been linked to water pollution, and it is becoming apparent that subsurface P losses can be substantial. The silty-loam Gleysol chosen for this study contained 146 mg Mehlich-3 P kg -1 , which exceeds the critical limit (66 mg Mehlich-3 P kg -1 ) for Québec. Equal quantities of fertilizer P (45 kg P ha -1 ) were applied from inorganic (triple superphosphate) and organic (composted cattle manure) sources to corn-corn and corn-soybean rotations. We evaluated crop production, the Mehlich-3 P and degree of soil P saturation levels, and the P concentration in subsurface water. Crop yields were unaffected by the fertilizer source, and only 31 to 67% of the P applied over a 2-yr period was exported, suggesting that the P fertilizer rate, chosen to match the P requirements of the corn crop, was excessive. After 2 yr, surface (0 to 15 cm) soils contained 149 to 199 mg Mehlich-3 P kg -1 and the Mehlich-3 (P/Al) saturation ratio (DSPS M3 ) ranged from 0.10 to 0.14. Subsurface water from piezometers installed to a 60-cm depth contained between 0.3 and 1.7 mg total P L -1 , and particulate P was the dominant P form at most sampling dates. Mehlich-3 P was positively correlated with dissolved reactive P, whereas the DSPS M3 was positively correlated with the total P and particulate P concentrations in subsurface water. We conclude that these soil test parameters could be useful indicators of subsurface P losses from Québec soils.Key words: Soil test P, degree of soil P saturation, composted cattle manure, triple superphosphate, P leaching Il existe un lien évident entre la sur-fertilisation des sols agricoles en phosphore (P) et la pollution des eaux. Le Gleysol limoneau choisi pour cette etude contiennait 146 mg kg -1 du P selon la méthode Mehlich-3 (Mehlich-3 P), excédant ainsi la limite critique (66 mg Mehlich-3 P kg -1 ) du Québec. Les quantités égaux d'engrais phosphorique (45 kg P ha -1 ) ont été appliqué en forme inorganique (superphosphate triple) et organique (fumier de bétail composté) sur les cultures en rotation maïs-maïs et maïs-soya. Nous avons evalué la récolte des cultures, la quantité du Mehlich-3 P, le degré de saturation du sol en P (DSSP), et la concentration du P dans l'eau sous-terrain. Les récoltes ont été nullement affecté par la source de fertilisant. Seulement 31 à 67% du P appliqué sur un period du deux ans a été exporté, ceci nous laissons à croire que la taux de fertilisation du P, recommendait au Québec, est excessif. Après deux ans, le sols du surface (0 à 15 cm) contiennait 149 à 199 mg Mehlich-3 P kg -1 puis la ratio du saturation en P (P/Al) selon la méthode Mehlich-3 (DSSP M3 ) a été entre 0.10 et 0.14. L'eau collectait d'un profondeur de 60 cm avec l'utilisation d'un pieometre contiennait entre 0.3 et 1.7 mg P totale L -1 . Le P en particules était la forme dominant du...

Development of a method for estimating the likelihood of crack flow in Canadian agricultural soils at the landscape scale

“…(1 or higher (Carefoot and Whalen 2003). During 25-yr, more than 81% of farmland remained in the same CF class, and 13% increased by at least one class (Table 4, Fig.…”

No-tillage and manure applications increase aggregation and improve nutrient retention in a sandy-loam soil

“…The soil is a Typic Endoaquent with 15.4 g total C kg À 1 , 1.24 g total N kg À 1 , 0.92 total P kg À 1 and pH 6.1 in the 0-to 15-cm sandy loam layer (containing, on average, 700 g sand kg À 1 , 140 g silt kg À 1 and 16 g clay kg À 1 ). Further details of the research site, and the effect of tillage, crop systems and fertilizer sources on soil fertility and soil physical properties have been reported (Carefoot and Whalen, 2003;Whalen et al, 2003).…”

Evaluation of phosphorus management practices in East Mediterranean altered wetland soils

“…A combination of common P‐application rates, public awareness and demand for sustainable farming practices, added to the increasing cost of P fertilizers, have prompted numerous studies showing that P is applied in excess of true requirements (Carefoot & Whalen, 2003; Valkama et al. , 2009).…”