Eugene J. Hogue

Influence of organic waste amendments on selected soil physical and chemical properties

Sandy, infertile soils can benefit from the addition of organic waste amendments. Annual applications of organic wastes for as long as 4 yr increased soil organic matter content, decreased soil bulk density, and increased soil water retention of a coarse-textured soil. However, soil water-holding capacity was not necessarily increased, and there was a limited effect on soil cation exchange capacity. Key words: Cation exchange capacity, water retention, soil pH, soil organic matter, soil bulk density

Effects of organic mulches on soil microfauna in the root zone of apple: implications for nutrient fluxes and functional diversity of the soil food web

A variety of organic materials (e.g. composts, paper recycling wastes, hay) can be used as in-row mulches in perennial horticultural cropping systems such as high density apple orchards. As organic materials with variable properties, such mulches can be expected to have variable effects on structure of the soil food web and mineralisation of N and P in the root zone. The overall objectives of this study were to: (1) assess the effects of a selection of organic mulches on the abundance of protozoa and nematode trophic groups; (2) use the model of Hunt et al. [Biol. Fertil. Soils 3 (1987) 393] to assess the implications of changes in microfaunal abundance for microbial turnover and N mineralisation; and (3) determine effects of the mulches on nematode indicators of increased microbial production/turnover and functional diversity of the soil food web. Organic mulch treatments commenced in 1994 and included shredded office paper, municipal biosolids, shredded paper applied over municipal biosolids, shredded paper applied over municipal compost, alfalfa hay, and black polyethylene fabric. The control was conventional tree-row weed management with glyphosate. Biosolids and municipal compost treatments were re-applied in 1997. Protozoan abundance was determined in 1998, 1999 and 2000. Nematode community structure was assessed in 1998, 1999, and twice in 2000. Nematode community parameters evaluated included: abundance of bacterivorous, fungivorous, omnivorous and predacious nematodes; abundance of the root-lesion nematode, Pratylenchus penetrans; absolute and relative abundances of enrichment opportunist nematodes (Rhabditidae+Diplogasteridae+Panagrolaimidae); Simpson’s diversity; evenness; and the indices of nematode community enrichment (EI) and structure (SI) described by Ferris et al. [Appl. Soil Ecol. 18 (2001) 13]. Measurements of the abundance of enrichment opportunists and the EI were evaluated as indicators of enhanced nutrient fluxes. Diversity and the SI were evaluated as indicators of changes in functional diversity of the soil food web. The abundance of protozoa and bacterivorous nematodes, and estimated fluxes of N and P through the microfauna, were greater under all combinations of biosolids or municipal compost and shredded paper than under the control and plastic mulch. The abundance of enrichment opportunist nematodes and the EI were also consistently greater under combinations of biosolids or municipal compost and shredded paper. The abundance of enrichment opportunists and EI were both also correlated with leaf P, providing additional evidence to support the use of these parameters as indicators of enhanced turnover of microbial biomass and nutrients. The SI was greatest under shredded paper and shredded paper applied over municipal compost, and least under municipal biosolids and alfalfa hay. Population densities of P. penetrans were reduced under shredded paper mulch relative to the control and biosolids alone.

Effect of soil cadmium application and pH on growth and cadmium accumulation in roots, leaves and fruit of strawberry plants (Fragaria × ananassa Duch.)

Three strawberry (Fragaria × ananassa Duch.) cultivars Rainier, Totem and Selva were grown under greenhouse conditions in a Parkhill sandy loam soil with a background DTPA-extractable Cd concentration of 0.18 mg kg-1 and a pH of 5.1. Experimental treatments included combinations of 4 Cd applications (0, 15, 30 and 60 mg Cd kg-1 soil) applied as CdSO4 and 2 soil pH values 5.1 and 6.8. Both the application of Cd and pH of the soil significantly affected plant growth, yield and Cd accumulation in plant tissue anf fruit. Although roots accumulated the highest concentrations of Cd of all plant parts investigated, increased soil Cd application reduced leaf weight more than root weight. In general, yield of strawberries was decreased by an increase in amount of soil-applied Cd, however the yield response varied among cultivars. At 60 mg Cd kg-1 soil, yield of Rainier cultivar was reduced to 17.6% of control plants. Over 90% of total Cd taken up by plants grown in Cd-treated soil accumulated in roots, regardless of the Cd level in the soil. Root Cd concentrations ranged from 2.6 mg kg-1 (control plants) to 505.7 mg kg-1 (Totem plants grown in soil at highest Cd and a soil pH 5.1) and were directly related to soil Cd concentrations. Cd translocation from roots to leaves and fruit was very limited, resulting in a maximum Cd concentration in root leaf tissue of 10.2 mg kg-1. Accumulation of Cd in fruit was found to correlate well with leaf Cd, although even at the highest amount of applied Cd, fruit Cd concentration did not exceed 700 μg kg-1 of fresh weight.

Surface application of mulches and biosolids affect orchard soil properties after 7 years

Changes in selected soil chemical and physical properties of a coarse-textured orchard soil were measured 7 yr after establishing different orchard soil management strategies which were deemed to be environmentally sound in a high-density apple orchard. Several locally available mulches and organic wastes applied to the soil surface were maintained and assessed as to their effect on tree performance and soil properties relative to a standard commercial practice involving maintenance of a weed-free herbicide strip (known as the “check” practice). The soil chemical status of these sandy soils was readily altered when large amounts of nutrients were contained in applied mulches and biosolids. Thus, elevated soil C [and cation exchange capacity (CEC)], N, P, Zn, Fe, Mn and Cu occurred after cumulative application of 90 t ha-1 of biosolids; soil pH and Ca content increased beneath a high-Ca shredded paper mulch, and soil was enriched in P and K beneath a high-PK alfalfa mulch. Small but statistically significa...

Evaluation of organic wastes as soil amendments for cultivation of carrot and chard on irrigated sandy soils

A field trial was designed to test the potential of various wastes as soil amendments in horticultural production. Swiss chard (Beta vulgaris L.) and carrot (Daucas carota L.) were grown during 1993–1995 under irrigation in a coarse-textured, British Columbia soil to which annual applications of 45 t ha−1 of various organic amendments plus NPK-fertilizers had been applied. The amendments included biosolids from Vancouver, Kelowna and Penticton, biowastes from Aldergrove and Abbotsford, and peat. Yield of both chard and carrot was increased for some organic treatments plus fertilizer relative to plots receiving commercially recommended rates of NPK-fertilizer only (control plots). Leaf N, P, Zn and Cu concentrations of both crops were usually elevated, but not to toxic values, in plots receiving wastes containing high concentrations of the respective nutrients. By the end of the third growing season, extractable P, Zn and Cu increased in the surface 15 cm of soil, relative to control plots, with P and Cu i...

Population dynamics of small mammals in relation to vegetation management in orchard agroecosystems: compensatory responses in abundance and biomass

Abstract This study was designed to test the hypothesis that habitat alteration with intensive herbicide (glyphosate) treatment would adversely affect the small mammal community in apple orchards. Multiple applications of herbicide were applied to the total orchard floor in two experimental orchards, and this same herbicide regime was applied in a 2-m-wide strip within tree rows only in a third orchard. Intensive sampling of montane vole ( Microtus montanus ), deer mouse ( Peromyscus maniculatus ), and northwestern chipmunk ( Eutamias amoenus ) populations was conducted in replicate control and treatment blocks of apple orchards at Summerland, British Columbia, Canada from 1983 to 1986. Average abundance of voles declined by 53% to 73% on treatment compared to control blocks after the first herbicide application. Vole populations were consistently reduced in response to the herbicide treatment, with average abundance ranging from 2.8 to 28.0 times higher on control than treatment blocks. Voles declined to, or near, extirpation in all orchards during the winter of 1985–1986. Either deer mouse and northwestern chipmunk populations were significantly higher on treatment than control blocks or there was no difference in abundance after the start of the herbicide applications. The average abundance of deer mice ranged from 1.3 to 11.1 times higher, and that of chipmunks ranged from 1.8 to 13.3 times higher, on treatment than control blocks. The high numbers of deer mice and chipmunks on treatment blocks were composed mainly of resident animals. There were no significant differences in biomass of small mammals between control and treatment populations in summer and winter periods in two out of three orchards. There appears to be a ‘compensatory response’ in this small mammal community whereby deer mice and northwestern chipmunks have essentially ‘replaced’ the montane vole on treatment blocks in an orchard agroecosystem. The quality of the altered habitats seemed sufficiently high to support these populations at comparable or higher levels than on controls. The species diversity of plants and animals in orchard agroecosystems should be investigated to determine their role as part of a mosaic of natural and agrarian habitats.

Ground cover influence on apple aphid, Aphis pomi DeGeer (Homoptera: Aphididae), and its predators in a young apple orchard

Abstract Four ground cover treatments were established in a young apple orchard to evaluate their effects on the apple aphid, Aphis pomi DeGeer, and its predators. The treatments were (1) fall rye, Secale cereale , herbicided in spring and summer; (2) white clover, Trifolium repens , and grass mixture; (3) herbicide strips with grassed alleys and (4) woven black plastic strips with grassed alleys. Seasonal tree terminal growth and leaf nitrogen in the clover-grass treatment were significantly lower than in the other three treatments in 1987 and terminal growth was significantly lower than in two of the other treatments in 1988, probably because of ground cover competition with the trees for nitrogen. Trees in the clover-grass treatment had total seasonal aphid and predator densities more than fourfold lower than trees in the other treatments in 1987, aphid and predator densities were more variable and not significantly different among treatments. Few ground cover predators were found except Lygaeidae, which rarely appeared in the trees. Terminals of trees in the non-clover treatments averaged 0.856 m of growth in 1987 despite carrying a mean of over 100 apple aphids per most infested terminal leaf for > 2 months.

Influence of diversionary foods on vole (Microtus montanus and Microtus longicaudus) populations and feeding damage to coniferous tree seedlings

Abstract This study was designed to test the hypotheses that diversionary food would: (1) reduce feeding by voles (Microtus spp.) to lodgepole pine (Pinus contorta) seedlings; and (2) provide a food source without increasing vole populations. Two experiments (A and B) were conducted with montane voles (M. montanus) in old field habitats at Summerland, British Columbia, Canada from 1996 to 1998. A third experiment (C) was conducted with long-tailed voles (M. longicaudus), meadow voles (M. pennsylvanicus), and southern red-backed voles (Clethrionomys gapperi) in young lodgepole pine plantations in forested areas in 1998–1999. Diversionary food was prepared in the form of “logs” composed of alfalfa pellets, wood pellets, or bark mulch mixed with wax and sunflower oil. Vole populations were intensively live-trapped on control and treatment sites. Mean percentage of seedlings eaten per vole was significantly reduced with bark mulch logs during a peak damage period in old field habitat. Alfalfa logs also tended to reduce seedling damage but only for the first month after placement. None of the diversionary foods tested had any effect on mean abundance of vole populations. In forest plantations, seedlings on control sites suffered mortality from vole feeding at levels 2.6–2.8 times higher than those on alfalfa and bark mulch sites. This difference was not statistically significant (P=0.09) but very likely was biologically significant in terms of seedling protection. This result was achieved with Microtus spp. on clearcut sites, but not on patch cut sites where red-backed voles were the most abundant microtine. The concept of seedling protection with these diversionary foods appears sound, but additional research is warranted.

Suitable orchard floor management strategies in organic apple orchards that augment soil organic matter and maintain tree performance

AimsOrganically-certified orchard floor management was assessed for its ability to improve soil fertility and biological activity and apple orchard performance.Methods‘Ambrosia’/B9 apple was maintained for the first six growing seasons with four orchard floor treatments, including 1) annual compost application; 2) in-row application of mown alfalfa grown between the rows; 3) bark mulch plus in-row application of mown hay; and 4) black plastic mulch.ResultsSoil collected from 0 to 10 cm indicated high soil organic matter and exchangeable K were measurable for all treatments by the second year. After 6 years, highest organic matter, total-, particulate- and mineral–C were associated with soil beneath the bark mulch treatment which also had most vigorous trees, decreased leaf N and elevated leaf P and K. Addition of alfalfa and bark mulch were equally effective at maintaining high exchangeable K and soil phosphatase enzymes, high total and particulate-N by the fourth year.ConclusionsDespite measurable improvements in soil properties among treatments, fruit yield and quality were minimally affected by management implying no limitations to adoption of any of the assessed strategies.

TEMPORAL CHANGES IN NITRATE STATUS OF ORCHARD SOILS WITH VARYING MANAGEMENT PRACTICES

Two anion exchange membrane systems (Plant Root Simulator probes and Dynambio nitrate selective anion exchange membranes) were evaluated as tools to estimate temporal changes in nitrate nitrogen (NO3-N) in the topsoils of four central Washington, USA apple orchards. Various management practices and different growing conditions were studied in the four orchards. Higher NO3-N was associated with increasing amounts of fertigated N, larger irrigation events, and surface application of alfalfa hay mulch and /or dairy compost. Nitrate nitrogen adsorbed by the membranes was lower when actively growing roots were present in the vicinity of the membranes, suggesting that uptake of NO3-N by apple tree and cover crop roots decreased the concentration of NO3-N in the soil solution. Thus, in the presence of plant roots, the estimate of the amount of phytoavailable NO3-N in the soil provided by the anion exchange membranes may be ambiguous. On the other hand, if roots can be excluded from the immediate vicinity of the membranes, the NO3-N adsorbed by the membranes may estimate the phytoavailability of NO3-N in the soil solution. Because anion exchange membranes provide information about the amount of NO3-N remaining in the soil after plant roots have met their demand, the membranes may be useful for estimating relative potential for NO3-N leaching. In summary, sequential use of anion exchange membranes appears to provide valuable information about temporal changes in the supply of soil NO3-N with various orchard management practices.