Keith Fuller

Potato Response to Phosphorus Fertilization at Two Sites in Nova Scotia, Canada

Identifying phosphorus (P) requirements and P-use efficiency is crucial to a sustainable potato industry in Eastern Canada. In a three-year study (2013–2015) conducted in Nova Scotia, Canada, we assessed the potato (CV Superior) yield response to P fertilization on two different soils in the Annapolis Valley. Soil organic matter ranged from 3.0% to 4.1% and from 2.0% to 2.5% at the Kentville and Sheffield sites, respectively. Initial soil phosphorus was higher at Kentville site, ranging from 81 to 162xa0mg kg−1 than at Sheffield site ranging from 75 to 109xa0mg kg-1. A randomized complete block design was used with five P rates (0, 17.5, 35, 52, and 79xa0kg P ha−1) applied at planting. Tuber yields were assessed at harvest, and P-uptake efficiency characteristics were measured before vine senescence. Total and marketable yields were not impacted by P rates. Marketable yield was 68% and 57% greater for Kentville than for Sheffield in 2013 and 2015, respectively and were significantly affected by P rates × year interactions at a 5.4% probability level. Quadratic functions were used to describe tuber yield responses to P rates (0.61xa0>xa0R2xa0<xa00.85) and P rates corresponding to the maximum yields were 17.5xa0kg P ha−1 in 2013 and 2015 and 35xa0kg P ha−1 in 2014 when data from both sites were pooled together. Phosphorus uptake efficiency ranged from 0.47 to 0.54xa0g DM mg−1 P offtake at Kentville and from 0.45 to 0.49xa0g DM mg−1 P offtake at Sheffield and was 13% and 7% greater at Kentville than at Sheffield in 2013 and 2015, respectively. While further studies are still needed for recalibration, results from this study provide some of the first information regarding potato response to P fertilization in Nova Scotia. Based on current P recommendations in the region for the same soil P levels, our results suggest that current P rates can be reduced without impacting potato yield.ResumenLa identificación de los requerimientos y de la eficiencia en el uso del fósforo (P) es crucial para una industria de la papa sustentable en el este de Canadá. En un estudio de tres años, desarrollado en Nueva Escocia, Canadá, evaluamos la respuesta al rendimiento de papa (var. Superior) a la fertilización con P en dos suelos diferentes en el valle de Annapolis. La materia orgánica del suelo fluctuó de 3.0% a 4.1%, y de 2.0% a 2.5% en las localidades de Kentville y Sheffield, respectivamente. El fósforo inicial del suelo fue más alto en Kentville, en una amplitud de 81 a 162xa0mg kg-1, que en Sheffield, variando de 75 a 109xa0mg kg-1. Se utilizó un diseño de bloques completos al azar con cinco niveles de P (0, 17.5, 35, 52, y 79xa0kg P haxa0−xa01) aplicados al momento de la siembra. Se analizó el rendimiento de tubérculo a la cosecha, y se midieron las características de eficiencia en la absorción de P antes de la senectud del follaje. Los rendimientos totales y comerciales no se impactaron por los niveles de P. El rendimiento comercial fue 68% y 57% mayor en Kentville que para Sheffield en 2013 y 2015, respectivamente, y se afectaron significativamente por las interacciones de los niveles de P x año a un nivel de probabilidad de 5.4%. Se usaron funciones cuadráticas para describir las respuestas de rendimiento de tubérculo a los niveles de P (0.61xa0>xa0R2xa0<xa00.85), y los niveles de P que correspondieron a los rendimientos máximos fueron de 17.5xa0kg P ha-1 en 2013 y 2015, y de 35xa0kg P ha-1 en 2014, cuando se juntaron los datos de ambas localidades. La eficiencia en la absorción de fósforo fluctuó de 0.47 a 0.54xa0g DM (materia seca) mg-1 de P tomado en Kentville, y de 0.45 a 0.49xa0g DM (materia seca) mg-1 tomado en Sheffield, y fue 13% y 7% mayor en Kentville que en Sheffield en 2013 y 2015, respectivamente. Mientras que aún se requieren más estudios para recalibración, los resultados de este estudio proporcionan algo de la primera información en relación a la respuesta de fertilización con P en Nova Scotia. Con base en las recomendaciones actuales en la región para los mismos niveles de P en el suelo, nuestros resultados sugieren que los niveles actuales de P pueden reducirse sin impactar el rendimiento de papa.

Grape Yield and Quality Response to Cover Crops and Amendments in a Vineyard in Nova Scotia, Canada

The increasing cost of synthetic fertilizers, combined with their associated environmental impacts and yield instability, has promoted the use of local waste products and cover crops in vineyards. We assessed the effects of cover crop mixtures combined with organic and industrial wastes on grape yield and quality over two full growing seasons in a vineyard (Vitis vinifera) in Eastern Canada. The experimental treatments were arranged in a nested design with three replicates. Four cover crop mixtures: (i) oats + pea + hairy vetch (OPV), (ii) oats mixed with red clover (ORCl), (iii) timothy + alsike + red clover (TM), and (iv) control with no cover crop (CONT) were applied to main plots and five fertility treatments (fertilizer without N [NDEF], full synthetic fertilizer [FERT], wood ash [WA], municipal solid food waste [MSFW], and mussel sediment [MS]) were applied to subplots. During the second growing season, only half of the subplots received fertility treatments. Grape yield for the most productive cover crop and amendment combinations were ORCl × MS (9.52 mg/ha) > OPV × MSFW (9.49 mg/ha) > TM × WA (8.81 mg/ha) > ORCl × MSFW (8.28 mg/ha). The lowest grape yields were obtained with combinations of CONT with either NDEF (3.86 mg/ha) or WA (3.61 mg/ha). The highest berry sugar concentrations among the cover crops were obtained under TM floor management combined with NDEF (16.43 Brix), MS (16.03 Brix), and MSFW (15.98 Brix). Grape yield was affected by cover crop only during the second growing season, but berry sugar was not. Cover crop floor management strategies and organic or industrial wastes can be used as sources of nutrients or soil conditioners for vineyards in the cool humid climate of Eastern Canada.

Effect of land management practices and environmental parameters on growing season denitrification rates under dairy crop rotations in Atlantic Canada

Abstract: Denitrification losses from agricultural land have been identified as a significant nitrogen (N) loss pathway that contributes to poor utilization of applied N. Higher losses have been reported when inorganic fertilizer N is substituted with an organic N source such as livestock manure. This research examines the relationships between denitrification rates, land management practices and soil processes when using spring applied liquid dairy manure (LDM) as principal N source. Mean daily denitrification rates (DDRs) in a perennial hayfield (PH) rotation and a corn-soybean-wheat (CSW) rotation with or without tillage (T and NT respectively) ranged between 0.9 and 27.0 g N ha-1 day-1. Mean, seasonal DDRs in the PH rotation were significantly lower in three out of six seasons when compared with the CSW-T and (or) CSW-NT rotation. When averaged across the six season study period, the mean DDR in PH of 4.4 g N ha-1 day-1 was also significantly lower than CSW-T and NT (7.6 and 8.1 g N ha-1 day-1, respectively). There were no significant effects of tillage in the CSW rotations in any of the six growing seasons. When treatment and growing season data were combined, a positive relationship between water-filled pore space (WFPS) and DDR indicated a threshold of approximately 40% WFPS for onset of significant denitrification. Similarly, the relationship between soil nitrate levels and denitrification rates in the population data set demonstrated that NO3- began to limit DDR below 2-5 mg N kg-1. This 6-year study of denitrification losses suggests a primary effect of WFPS, a secondary effect of O2 consumption as reflected by soil respiration, and nitrate limiting only at relatively low concentrations. Environmental variables were more consistent drivers of denitrification in three manure-fed crop rotations typical of Atlantic Canada dairy operations than were land management decisions and practices.