Soil inorganic nitrogen content in commercial potato fields in New Brunswick

2003 ◽  
Vol 83 (4) ◽  
pp. 425-429 ◽  
Author(s):  
B. J. Zebarth ◽  
Y. Leclerc ◽  
G. Moreau ◽  
R. Gareau ◽  
P. H. Milburn

Information on inorganic N content in commercial potato fields in Atlantic Canada is limited. Soil inorganic N measurements were collected from 228 commercial potato fields from 1999 to 2001. Soil NO3 content to 30 cm depth at planting ranged from 2 to 124 kg N ha-1, and was generally higher for preceding potato, red clover, or hay crops compared to preceding cereal or other crops. Soil NH4 content to 30 cm depth measured at planting ranged from 3 to 64 kg N ha-1, indicating that both soil NO3 and NH4 need to be measured to assess plant-available soil N content in spring. Soil NO3 content to 30-cm depth at tuber harvest ranged from 3 to 250 kg N ha-1, generally increased with increasing fertilizer N application rate, and differed among different potato cultivars. Soil NO3 content measured to 30-cm depth in spring ranged from 3 to 100% of soil NO3 at harvest in the preceding fall, indicating that highly variable losses of soil NO3 from the root zone occur between growing seasons. Key words: Nitrate, ammonium, Solanum tuberosum L.

2021 ◽  
Author(s):  
Carlo Alberto Dominguez-Eusebio ◽  
Oscar Luis Briones ◽  
Yareni Perroni

Abstract Understanding the matter and energy dynamics in environments with strong human influence is essential since it allows us to know relevant ecological drivers in urban green land areas. It has been hypothesized that biogeochemical cycles in urban forests are more open (susceptible to nutrients soil losses) with respect to rural forests near cities. However, it is not clear if this ecosystem function occurs in the same way in systems from different latitudes. Soil nutrient dynamics and microclimatic conditions of an urban and a nearby rural montane cloud forest were registered from January 2016 to July 2017. Our objective was to compare edaphic and micro-climatic factors that drive soil inorganic N dynamics in these forests. Climate was slightly cooler and drier, and soil C, N, P and organic matter were lower in the urban than the rural forest. Seasonal soil inorganic N forms were related to above ground conditions in the urban forest, but to the belowground conditions in the rural forest. Consistently low NH4:NO3 ratio indicated high susceptibility to N soil loss in the urban forest. Our results support the hypothesis that urban cloud forests are functioning as open ecosystems in contrast to the rural forests.


Agronomy ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 983
Author(s):  
Peyton Ginakes ◽  
Julie M. Grossman

Winter annual legume cover crops often fail to reach full maturity by spring vegetable planting dates in northern climates, which prevents maximum nitrogen (N) contributions. To determine if delayed termination improved cover crop biomass and N content, we evaluated winter rye + hairy vetch (Secale cereale L. + Vicia villosa Roth) and oat + field pea (Avena sativa L. + Pisum sativum L.) cover crop mixtures in 2015 and 2016, and medium red clover (Trifolium pratense L.) in 2016, in zone-tilled organic yellow crookneck squash (Cucurbita pepo var. torticollis Harz). In-row regions where cover crops were terminated in early spring during crop row preparation were compared to between-row regions where termination was delayed until legume maturation in late spring. Soil quality (soil inorganic N, permanganate oxidizable C (POXC), and potentially mineralizable N (PMN)) was also determined for in-row and between-row regions at four time points throughout the growing season. In 2015, winter rye + hairy vetch biomass N more than doubled between early and late termination times, with 120 and 258 kg N ha−1, respectively. Permanganate oxidizable C was not responsive to cover crop systems or tillage, and only slightly decreased over time in 2016. Soil inorganic N and PMN after cover crop termination in 2016 provided evidence of localized soil N cycling responses to cover crop termination in in-row and between-row regions. The extended growing period for cover crops between crop rows in the first several weeks of crop growth had no negative effect on crop yield, and appeared to enhance soil fertility.


2020 ◽  
Vol 59 (1) ◽  
pp. 12-26 ◽  
Author(s):  
T. Moloney ◽  
H. Sheridan ◽  
J. Grant ◽  
E.G. O’Riordan ◽  
P. O’Kiely

AbstractBinary- and multi-species sown mixtures may increase herbage yield and/or reduce inorganic nitrogen (N) requirement compared to perennial ryegrass (PRG) (Lolium perenne L.) swards. A split-plot design was used to compare yields of binary- and multi-species mixtures to single-species swards of three grasses and red clover managed for intensive silage production under varying N application rates. Perennial and Italian (Lolium multiflorum Lam.) ryegrasses had greater annual yields when grown as single species receiving 360 kg N/ha per year than in binary mixtures with red clover (Trifolium pratense L.) receiving 0 kg N/ha per year, whereas timothy (Phleum pratense L.) produced equally high yields in both situations. When no inorganic N was applied, the annual dry matter yield of Mix 1 (10,738 kg/ha; PRG, timothy, red clover and white clover (Trifolium repens L.) and Mix 2 (11,679 kg/ha; PRG, timothy, red clover, ribwort plantain (Plantago lanceolata L.) and chicory (Cichorium intybus L.)) was greater than that of a PRG sward (PRG/0N; 5,885 kg/ha) and derived more from the contribution of legumes than herbs. This yield advantage of mixtures declined as inorganic N input increased, as did the legume and herb proportions in the multi-species swards. When averaged across rates of inorganic N input, Mix 2 had a greater annual yield than Mix 1 (12,464 vs. 11,893 kg/ha). Mix 2 receiving no inorganic fertiliser N and both Mix 1 and Mix 2 receiving 120 kg N/ha per year matched the annual yield achieved by PRG receiving 360 kg N/ha per year. Our results indicate that the yield performance of binary- and multi-species grassland swards should be measured in situ rather than predicted from single-species swards of constituent species.


Plant Disease ◽  
1997 ◽  
Vol 81 (7) ◽  
pp. 831-831 ◽  
Author(s):  
M. Sedegui ◽  
R. B. Carroll ◽  
A. L. Morehart ◽  
A. Arifi ◽  
R. Lakhdar

Late blight of potato (Solanum tuberosum L.) caused by Phytophthora infestans (Mont.) de Bary first appeared in Africa in 1941. It has been observed sporadically in Morocco for decades but only recently became a major problem. Significant losses have been recorded in the last two growing seasons in spite of the use of various disease control programs that included combinations of systemic and protectant fungicides. Phytophthora infestans was cultured from diseased foliage collected from commercial potato fields near Larache, Morocco. Isolates were analyzed to determine pathogenicity on several potato and tomato cultivars, mating type, genotype at two allozyme loci (2), and relative sensitivity to metalaxyl. Responses of the isolates to metalaxyl were assayed by mycelial radial growth on metalaxyl-amended agar, by floating leaves inoculated with P. infestans on metalaxyl solutions, and via potato tuber disks placed on filter paper saturated with metalaxyl solutions (1). Koch's postulates were completed; all isolates were pathogenic to potato and tomato cultivars tested, are consistent with the A1 mating type, and have the same allozyme pattern (Gpi 100/100, Pep 92/100) as US-6 genotype. All tests indicated resistance to metalaxyl up to 250 ppm. References: (1) K. L. Deahl et al. Am. Potato J. 70:779, 1993. (2) S. B. Goodwin et al. Plant Dis. 79:1181, 1995.


2018 ◽  
Vol 98 (3) ◽  
pp. 517-526 ◽  
Author(s):  
M.S. Thilakarathna ◽  
Y.A. Papadopoulos ◽  
M. Grimmett ◽  
S.A.E. Fillmore ◽  
M. Crouse ◽  
...  

Plant and environmental factors affect root nitrogen (N) exudation dynamics in legumes. To better understand the genotypic variability and plant factors affecting root N release nodulation, plant growth, tissue N content, and root N exudation, six (three diploid and three tetraploid) red clover (Trifolium pratense L.) varieties were evaluated under controlled environmental conditions during the first 8 wk of plant growth after rhizobia inoculation. Genotypic differences were found for nodulation, plant dry weight (DW), leaf area, root attributes (root length, surface area, volume, and diameter), shoot and root N concentration, and N content. Genotypic differences were also found for root exudate N content in terms of NO3−-N, NH4+-N, and dissolved organic N (DON). In general, root exudate inorganic N content was greater in tetraploid varieties than in the diploids throughout the growth period. Root exudate DON content was greater than the inorganic N content. The NO3−-N content in root exudate was positively correlated with root growth attributes and root N concentration, whereas NH4+-N content was positively correlated with nodule number. Root exudate DON was positively correlated with shoot N concentration and average nodule DW. These results highlight the existence of genotypic differences among red clover varieties for plant morphological factors affecting root N release during the early stages of plant development.


1996 ◽  
Vol 11 (4) ◽  
pp. 182-189 ◽  
Author(s):  
Julia B. Nelson ◽  
Larry D. King

AbstractInterest in developing more sustainable cropping systems has led to renewed interest in legumes as N sources for crops. We conducted a 2-year study to compare the effects of green manure, green manure plus fertilizer, and fertilizer on wheat yield and N leaching potential. In 1991–92, wheat following corn and receiving 0, 45, or 90 kg N/ha was compared with wheat planted after plowing the autumn regrowth of red clover/johnsongrass hay (supplemented with alfalfa) that supplied 107 kg total N/ha. In 1992–93, wheat following corn and receiving 90 kg N/ha was compared with wheat following hay regrowth that either received fertilizer N at 45 kg/ha or 90 kg N/ha or was supplemented with alfalfa (total of 123 kg N/ha). Yield with only green manure averaged 65% of yield with 90 kg N/ha. Yields with green manure plus 45 or 90 kg N/ha were not different from yield with 90 kg N only. The first year, soil to a depth of 30 cm declined from as high as 40 kg/ha in the fall to less than 10 kg/ha as wheat growth increased in the spring. In contrast, concentration averaged 20 kg/ha throughout the growing season. Trends in soil inorganic N were similar the second year. Profile nitrate distribution indicated a greater potential for N leaching with fertilizer than with green manure. Soil from the site was used in a laboratory incubation study to determine the rate of N mineralization from white clover at 10°C. An average of 80% of the clover N was recovered as soil inorganic N; however, in the field study, recovery (soil inorganic N in the 0 to 30-cm zone + Nin above-ground wheat biomass) was only 21%. Supplementing green manures with spring applications of fertilizer N could decrease the leaching loss without decreasing wheat yield.


2003 ◽  
Vol 83 (2) ◽  
pp. 183-195 ◽  
Author(s):  
B. J. Zebarth ◽  
P. H. Milburn

The purpose of this study was to determine the spatial and temporal variation in soil inorganic N concentration in the potato hill, and to discuss the implications of this variation on soil sampling strategies. The experiment was conducted in 1999 and 2000 using four treatments: bare soil with no N fertilizer applied, and a potato crop with no fertilizer N added, with 180 kg N ha-1 applied at planting, or with 120 kg N ha-1 applied at planting plus 60 kg N ha-1 applied at hilling. Elevated (above background) soil NH4+-N concentrations were measured for 40 or more days after planting, therefore in-season sampling should be done for both soil NO3−-N and NH4+-N. There was a period of up to 50 days between planting and rapid crop N uptake during which loss of NO3−-N from the root zone could occur. Split fertilizer application reduced the risk of NO3−-N loss during this time, but resulted in reduced tuber yield in 1999. Strong vertical variation in soil inorganic N concentration was measured in the potato hill as a result of fertilizer banding and soil N mineralization at shallow depths. Soil inorganic N concentrations were elevated in the hill, but not in the furrow, resulting in strong horizontal variation in soil inorganic N concentrations in the potato hill. Despite this variation, a systematic sampling strategy where soil was sampled in the centre of the hill, the centre of the furrow, and mid-way between the hill and furrow, done in combination with elevation control of soil sampling, resulted in an unbiased estimate of soil inorganic N concentration in the potato hill. Key words: Solanum tuberosum, nitrification, nitrate leaching, mineralization, sampling strategies


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