Y. K. Soon

Nitrogen release during decomposition of crop residues under conventional and zero tillage

Nutrient cycling is an important part of integrated nutrient management. The litterbag method was used in field experiments to determine potassium (K) release patterns from red clover (Trifolium pratense) green manure (GM), field pea (Pisum sativum), canola (Brassica rapa) and monoculture wheat (Triticum aestivum) residues under conventional and zero tillage from 1998 to 1999 and from 1999 to 2000. Potassium contained in crop residues ranged from 25 kg ha-1 in wheat to 121 kg ha-1 in pea residues, both under zero tillage. The percentage of K released over a 52-wk period ranged from 65% of pea K under zero tillage to 99% of clover K under conventional tillage, and the amounts released were 20–32 kg ha-1 from wheat, 31–52 kg ha-1 from canola, 28–79 kg ha-1 from pea, and 31–118 kg ha-1 from legume GM residues. In both trial periods, K from wheat residues was released at a faster rate under conventional tillage than under zero tillage during the first 10 wk of residue decomposition. In contrast, K from pea an...

Crop residue and fertilizer management effects on some biological and chemical properties of a Dark Grey Solod

A 10-yr experiment was initiated on a Dark Grey Solod near Beaverlodge, Alberta (55° 13′N, 119° 20′W) in 1985 to determine the effects of fertilizer management and barley (Hordeum vulgare L.) straw removal or incorporation on soil organic carbon (SOC) and related properties. Four crop residue treatments viz., (i) straw removed; (ii) straw ploughed in; (iii) straw disked in; (iv) straw disked in, plus a red clover (Trifolium pratense L.) green manure disked in every fifth year were superimposed on each of four fertilizer treatments. The fertilizer treatments were application of N and P: (i) banded at soil-test recommended rates (ST, b); (ii) broadcast-applied and incorporated at soil-test recommended rates (ST, bi); (iii) banded at soil-test rates of N + 25 kg ha−1 and of P + 10 kg ha−1 (ST +, b); (iv) as in (iii) but fertilizers broadcast-applied and incorporated (ST +, bi). Each treatment was replicated three times in a strip-plot design. Organic carbon, total nitrogen, total, organic and inorganic phosp...

Eight years of crop rotation and tillage effects on crop production and N fertilizer use

Although tillage systems and crop rotations can affect crop production and uptake of nutrients, their long-term effects, particularly their interactions, are not well-documented. Therefore, we measured the N, P, and K contents and yields of crops through two rotation cycles, especially wheat (Triticum aestivum L.), of four crop rotations managed under conventional tillage (CT) and no-tillage (NT) systems. The study was conducted 1993 through 2000 on a sandy loam soil in northwestern Alberta, Canada. The four-course crop rotations were: (i) field pea (Pisum sativum L.)-wheat-canola (Brassica rapa L.)-wheat; (ii) red clover (Trifolium pratense L.) green manure-wheat-canola-wheat; (iii) fallow-wheat-canola-wheat, and (iv) continuous wheat (CW). The crops were fertilized using regional recommendations based on soil test results. Previous crop effect on wheat yield was in the order: field pea = red clover green manure > fallow > canola > wheat (CW); it had little influence on N, P or K content in wheat grain o...

Soil nutrient stratification and uptake by wheat after seven years of conventional and zero tillage in the Northern Grain belt of Canada

The distribution of NaHCO3-extractable nitrate-N, ammonium-N, phosphorus (P) and potassium (K) with soil depth (0 to 20 cm in 5-cm increments) at Fort Vermilion (58°23′N 116°02′ W), Alberta, was described in the 7th and 8th years of conventional and zero tillage following placement of red clover (Trifolium pratense) green manure (GM), field pea (Pisum sativum), canola (Brassica rapa) and monoculture wheat (Triticum aestivum) residues. Soil nitrate-N concentrations under zero tillage were greater than those under conventional tillage in the 0–5 cm soil layer, below which the concentrations were similar. Ammonium-N and K concentrations followed a similar pattern. However, soil P concentrations were usually not different between tillage systems in the 0–5 cm soil layer, but the concentrations decreased more under zero tillage than under conventional tillage at lower depths. A notable exception for soil phosphate was under canola residues, where the concentration was greater under zero tillage than under conv...

Influence of controlled-release urea on seed yield and N concentration, and N use efficiency of small grain crops grown on Dark Gray Luvisols

Field experiments were conducted on Dark Gray Luvisolic soils (Typic Cryoboralf) from 2004 to 2006 (wheat-canola-barley rotation) near Star City, Saskatchewan, and from 2004 to 2007 (barley-canola-wheat-barley rotation) near Beaverlodge, Alberta. The aim was to compare the effects of controlled-release urea (CRU) vs. conventional urea (hereafter called urea) on seed yield and N (i.e., protein) concentration, and N use efficiency (NUE). The treatments were combinations of tillage system [conventional tillage (CT) and no tillage (NT)], and N source (urea, CRU and a blended mixture), placement method (spring-banded, fall-banded and split application) and application rate (0-90 kg N ha-1). There was no tillage × fertilizer treatment interaction on the measured crop variables. Seed yield and crop N uptake and, to a lesser degree, seed N concentration generally increased with N application to 90 kg N ha-1. Fall-banded CRU or urea generally produced lower crop yield and N uptake than spring-banded CRU or urea. S...

Recovery of chemical and physical properties of boreal plain soils impacted by pipeline burial.

Pipeline construction on the Canadian boreal plain occurs on woodland and/or agricultural fields, but soil recovery from its impact is not well documented. Therefore, we quantified changes over 3 yr (1992 to 1994) in the chemical properties of two Grey soils and the physical properties of a Grey soil that were subjected to pipeline burial and cropped to barley. The pipeline right-of-way (RoW) was divided into three zones: a road (or work) area used for vehicular traffic, a trench area for burying pipeline, and a pile (or spoil) area where soil was stockpiled during excavation. Pipeline construction resulted in mixing of subsoil material with topsoil, and the chemical properties most affected were those that varied most with depth. The pH, electrical conductivity, soluble sulphate, and exchangeable Ca and Na were increased in the surface 20 cm of soil, particularly the road and trench areas. The affected properties moderated 2 or 3 yr after pipeline construction as soluble components were dissolved or disp...

Soil microbial response to wood ash or lime applied to annual crops and perennial grass in an acid soil of northwestern Alberta.

More than 90% of acid soils in western Canada are in Alberta, yet the use of agricultural lime is limited because it is expensive. Wood ash, a by-product of pulp and lumber mills, can be used for liming acid soils. We investigated the effects of amending an acid Luvisol with wood ash or lime on soil microbiological properties at Beaverlodge, Alberta. Both soil amendments were applied at a calcium carbonate rate of 6.72 t ha-1, which was 8.40 t ha-1 for wood ash and 7.47 t ha-1 for lime, in 2002. Soil microbial biomass C (MBC) and the functional diversity and community structures of soil bacteria (indicated by substrate utilization patterns) were measured from 2002 to 2005 under barley (Hordeum vulgare L.), canola (Brassica napus L.), field pea (Pisum sativum L.), and timothy grass (Phleum pratense L.). In the rhizosphere, wood ash increased soil MBC between 2.4-fold in 2002 and 1.3-fold in 2005, and lime increased MBC from 3.2-fold in 2002 to 1.3-fold in 2005. In bulk soil, the increases in MBC ranged fro...

Carbon and nitrogen contents of different-sized light fraction organic matter as influenced by tillage and residue management.

The light fraction (LF) has a variable elemental content because it comprises a pool of soil organic matter that is in transition between fresh residues and stable, humified organic matter. Our aim was to assess the influence of time, tillage (CT vs. NT) and straw management (removed or retained) practices on the C and N contents of two particle sizes of LF materials from a Gray Luvisol in Alberta. The LF C and N concentrations were not affected by tillage and straw treatments. The C concentration was higher in LF > 1 mm (coarse LF) than in the < 1 mm LF (fine LF), while the converse was observed for N concentration, resulting in C:N ratios of 45-59 in the coarse fraction and 18-19 for the finer materials. The C concentration of the fine LF decreased and the N concentration increased with time. After 4 yr, LF C and N stocks were higher under NT than under CT mainly because of faster decomposition of litter under CT. Retaining straw resulted in bigger increases in C and N stocks in the coarse LF compared w...

Effect of pipeline installation on crop yield and some biological properties of boreal soils

Pipeline construction on the Grey soils of the Canadian boreal plains, which have a thin Ah horizon, could have considerable impact on their properties and productivity. This study was conducted because the effects of pipeline installation on crop yield and biological properties of these soils have not been well-documented. Soil was sampled from a Grey Luvisol and a Dark Grey Solod prior to pipeline construction in 1991, and in each of the following 3 yr. The right-of-way (RoW) was divided into three zones: a road (or work) area used for vehicular traffic; a trench where the pipeline was buried; and a pile (or spoil) area where soil was stockpiled during construction. The RoW was cropped to barley (Hordeum vulgare L.) in 1992 through 1994. Barley yield was low in 1992 (830–1120 kg ha−1), and near average (2050–3290 kg ha−1) in 1993 and 1994. Except for low shoot P concentration (1.1–1.3 mg g−1) in 1992, macronutrient concentrations (N, P and K) in barley tissues were within normal ranges. Soil organic car...

Crop residue and fertilizer management effects on nutrient use and barley production

Cereal straw has many potential on-farm and off-farm uses. If straw is to be removed from land, the practice should not adversely impact long-term crop production and soil quality. A 10-yr experiment was conducted on a Dark Grey Solod near Beaverlodge, Alberta (55°13′N, 119°20′W) to determine the effects of fertilizer and straw management on the yield of, and nutrient (N and P) use by, continuous barley (Hordeum vulgare L.). Four straw management treatments: (i) straw removal; (ii) straw ploughed in; (iii) straw disked in; and (iv) straw disked in plus a red clover (Trifoleum pratense L.) green manure disked in every fifth year, were superimposed on four fertilizer treatments. The fertilizer treatments were application of N and P: (i) banded at soil-test recommended rates (ST,b); (ii) broadcast and incorporated at soil-test recommended rates (ST,bi); (iii) banded at soil-test rates of N+ 25 kg ha−1 and P+ 10 kg ha−1 (ST+,b); and (iv) as in (iii) but broadcast-applied and incorporated (ST+,bi). The straw p...