Soil and crop responses to long-term potato production at a benchmark site in northwestern New Brunswick

Abstract

Concerns about deteriorating soil quality led to Agriculture and Agri-Food Canada establishing a network of 23 soil quality monitoring benchmark sites with the objective of providing a baseline data set for assessing change in soil quality and biological productivity of representative Canadian farming systems. A site (22-NB) was established in 1990 in northwestern New Brunswick to monitor changes in Podzolic and Brunisolic soils developed on coarse loamy till on a rolling landscape under intensive potato (Solanum tuberosum L.) production [potato-potato-barley (Hordeum vulgare L.) rotation] that was cultivated along the contour with variable grade diversions and a grassed waterway. Soil samples were collected in 1990 and again in 2000. Field saturated hydraulic conductivity (Kfs) at 10–20, 26–36 and 50–60 cm, earthworm counts and crop yield measurements were conducted annually. 137Cs data were collected in 1990 to estimate soil displacement at the site. Runoff and soil loss between May 01 and Nov. 30 were measured annually. The soil conservation system at site 22-NB has resulted in annual runoff and soil loss of only 9 mm and 311 kg ha-1, respectively. Measured values of 137Cs averaged 2114 Bq m-2 (70% of baseline). Changes in the Ap horizon properties between 1990 and 2000 included significant (P < 0.05) increases in available P (+ 86.7 mg kg-1) and K (+ 13.4 mg kg-1) and significant reductions in available Mg (−45.8 mg kg-1) and SOC (−0.51 g kg-1). The Kfs of 10- to 20-cm, 26- to 36-cm and 50- to 60-cm depths were 1.3, 1.0 and 1.0 cm h-1, respectively. Very few earthworms were present (0.05 worms m-2). The upper terrace was consistently the highest yielding in both potato and barley, while the lowest terrace was consistently the lowest yielding in both crops. Crop yields may have been affected by micro-climate and other soil differences as a result of site position.While the system of contour tillage with variable grade diversions and grassed waterway conserved both soil and water, the potato-potato-grain rotation did not maintain SOC levels or sustain earthworm populations. Associated heavy rates of fertilization also lead to increased levels of soil K and P. Key words: Soil quality, soil organic carbon, hydraulic conductivity, earthworms, runoff, water erosion

Impacts of soil and water conservation practices on potato yield in northwestern New Brunswick, Canada

“…resulting from site position (e.g., flat, steep slope, riverine, etc.) (Rees et al 2008). Inclusion of farm dummy variables also acted as a control for omitted variables and accounted for unobserved time-invariant characteristics that might be correlated with the dependent variable.…”

“…In another New Brunswick study, Chow et al (1999) found that terraces and grassed waterways reduced runoff and soil loss, thereby increasing available water for plant growth. Rees et al (2008) found that upper terrace cross sections within a field consistently had higher potato yields compared to the lowest terrace. They reasoned that potato yields may have been affected by microclimate and other site position soil differences.…”

“…Research has shown mixed results associated with BMP impacts on soil, water, and yield conditions in the province (Chow et al 2011(Chow et al , 2007(Chow et al , 1999(Chow et al , 1992Rees et al 2008;Carter et al 2005;Daigle 1983). Chow et al (1992) found that rock management (rock picking and crushing) reduced the number of injured tubers when using mechanical harvesters, degraded soil quality, and increased runoff and soil loss potential.…”

Brunisolic soils of Canada: Genesis, distribution, and classification

“…They are the least common of the Brunisols, with total aerial extent of 21 500 km 2 . (Wang et al 1984;Rees et al 2008). An example of a cultivated Orthic Sombric Brunisol from the Fraser River Delta in British Columbia is given in Fig.…”

“…Long-term mineral fertilizer additions to the Fredericton loam sustained timothy hay production in the Saint John River valley (Rees and Fahmy 1984) and years of manure application to the Pitt's Pond soil in central Newfoundland have significantly increased forage production (Hender 1986).…”