Peat Treatments Research Articles

Influence of Fertilizers Applied to a Paddy−Upland Rotation on Characteristics of Soil Organic Carbon and Humic Acids

The qualitative and quantitative characteristics of soil organic carbon (SOC) and related humic acids (HAs) extracted from the soils of field plots were investigated after 8 years of annual paddy (Oryza sativa L.) and upland maize (Zea mays L.) rotation with various fertilizations. Seven fertilization treatments were selected: Ck (no inputs); Chem (chemical fertilizer of NPK); Comp (swine compost); Comp + 33% of Chem N rate; Comp + 67% of Chem N rate; GM (legume green manure) + 33% of Chem N rate; and peat + 33% of Chem N rate. Organic and inorganic nitrogen inputs of six treatments were equivalent with respect of nitrogen content, but Comp, GM, and peat treatments were complemented with various amounts of inorganic N. After harvest of the eighth paddy crop, surface soil samples collected from the plots were subjected to soil characterizations and extraction of humic substances, which were used for chemical, spectroscopic (FTIR, 13C NMR, ESR, X-ray diffractometry), delta13C, and 14C dating analyses. The yields of HAs extracted from the seven treatments were significantly different. Treatment containing persistent organic compound such as the peat + 33% N treatment increased the humification process in topsoils and produced higher yield of HA. Spectroscopic analyses revealed that fertilization treatments changed the functional groups, alkyl C, crystalline characteristics, and delta13C ratios of HAs and turnover rate of SOC considerably. The SOC of the peat + 33% N treatment had the highest mean residence time of 3100 years. Various fertilizer treatments are correlated with turnover rate of SOC and related HAs, which are associated with concerned carbon sequestration as well as mitigation of CO2 emission in the soil environment.

Cropping history and peat amendment-induced changes in strawberry field earthworm abundance and microbial biomass

Common agricultural practices, e.g. soil tillage and organic amendment, may affect field earthworm communities considerably. However, there is little data to show how long the changes persist after a certain action. The effect of peat, commonly used in Finland to improve the horticultural soil structure, on key soil organisms is also largely unknown. Earthworm abundance and microbial biomass were studied in a strawberry field experiment (soil type silty clay) with a history of different crops (strawberry, timothy, caraway, rye, turnip rape, fiddleneck, onion and buckwheat) and peat treatments. Sampling was carried out after three years of perennial cropping of strawberry. Half of the area was peat-amended twice three years apart. The earthworm community consisted mainly of Aporrectodea caliginosa and Lumbricus terrestris. Soil peat amendment almost doubled the number of endogeic A. caliginosa, but had no effect on the anecic L. terrestris. The effect of cropping history on earthworms diminished after three years of strawberry cropping. Only the positive effect of caraway on juvenile Lumbricus spp. was detectable three years after its cropping had been finished. However, some crops had secondary effects on the earthworm distribution without significant influence on their numbers while they were grown, e.g. high numbers of A. caliginosa were recorded from soil with a history of timothy ley. The effect of strawberry cropping was contradictory: six years of continuous strawberry cropping decreased the number of the anecic L. terrestris, but during the last three years on strawberry, the proportion of L. terrestris increased from 6% to 40% in the experimental area with a concomitant great drop in the number of A. caliginosa. The role of different agricultural practices (no tillage, mulching, inter-row grass cover and pesticides) is discussed. The crop-induced changes persisted in the microbial biomass for three years (onion cropping reduced microbial biomass C), but soil amendment had no effect on microbes. The abundance of A. caliginosa was associated with soil organic C, but not with soil microbial biomass.

Potential of Sphagnum peat for improving soil organic matter, water holding capacity, bulk density and potato yield in a sandy soil

Low soil organic matter content and limited soil water holding are the major natural constraint of dryland cropping on sandy soils in the Quebec boreal regions. We conducted a 3-yr (1994–1996) study in a boreal sandy soil, Ferro-Humic Podzol (Spodosols), to determine the potential of Sphagnum peat for improving soil organic matter (SOM), water holding capacity, bulk density (BD), plant leaf nutrient status, and potato and barley yields. The cropping was a rotation of 2-yr potato (Solanum tuberosum L. ‘Superior’) and 1-yr barley (Hordeum vulgare L. ‘Chapais’). The treatments consisted of Sphagnum peat at rates of 0, 29, 48, and 68 Mg ha−1 3-yr−1 on a dry weight basis, and granular N-P-K fertilizers (12-7.5-7) at rates of 1.4, 1.6, and 1.8 Mg ha−1 yr−1, respectively, arranged in a split-block design. The peat-amended soils were higher in water content (SWC), SOM and total porosity but lower in BD and N than neighboring non-peat soils (P < 0.05). Effects of peat and fertilizer treatments and their interaction were significant on potato leaf N, Ca, Mg, and P, tuber yield, dry weight, harvested N and tuber specific gravity (P < 0.05), depending on year. Potato tuber yield and N increased simultaneously up to 30% (compared to the control), and were significantly correlated with SWC, SOM, BD, and NO3-N (−0.52 ≤r ≤ 0.80). In the 3rd year, the linear effect of peat treatments was significant on barley grain yield. In 1995 there was a decline of 4.5−7.3% of SOM of the previous year level. It is suggested that Sphagnum peat at a rate of 48 Mg ha−1 had the potential for improving sandy soil productivity. A longer-term investigation of soil water, N, SOM pool and crop yield changes is necessary to better understand the physical, chemical and biological processes of peat in cropping systems and to maximize the benefits of peat applications.

The impact of crop plant cultivation and peat amendment on soil microbial activity and structure

A rapid means for restoring soil fertility could be addition of peat to the plough layer. The impact of cultivation of eight different crops (the joint impact of plant and the management tailored for each plant), with and without soil amendment by peat treatment on soil microbiological, physical and chemical properties was assessed for two consecutive growing seasons. As a measure of the functional diversity of soil microbial community we estimated the activity of several different extracellular soil enzymes using the ZymProfiler® test kit. ATP content was measured to yield information on the amount of the active microbial biomass, and phospholipid fatty acid (PLFA) profiles were analysed to reveal the microbial community structure. The enzyme activity patterns of the soil samples indicated several differences due to the different crops and years but ATP content and PLFA profiles were rather stable. However, microbial biomass as total amount of PLFAs depended on the plant and peat treatment and ATP content varied between the years. The effects of the peat treatments were less clearly indicated by the biological parameters one or two years after the amendment, as only arylsulphatase and β-xylosidase activities were affected in both the years. Soil moisture, affecting enzyme activities, depended on the year and crop plant and peat addition increased it.

Arbuscular Mycorrhiza and Growth Responses of Several Ornamental Plants Grown in Soilless Peat-based Medium Amended with Coconut Dust (Coir)

Coconut fiber dust (coir) is being used as a peat substitute or amendment to potting mixes with varied results. However, its microbial composition and compatibility with beneficial microbes that might be added to growth media in the nursery, such as mycorrhizal fungi, has not been determined. In this study, coir was amended to a peat-based medium (15%, 30%, 45%, and 60% by volume) to determine its effects on growth of several ornamental plants and on the formation and function of the arbuscular mycorrhizal (AM) fungus Glomus intraradices. Mycorrhizae formed as well, and usually better, in all the coir-amended peat treatments as in peat alone. The magnitude of growth enhancement due to mycorrhizae was small for the plants tested in these media compared to that which usually occurs in soil-based media. In this experiment, plant growth responses appeared to be independent of level of mycorrhizal colonization and were plant species dependent. Consistent growth enhancement from mycorrhizae only occurred with marigold (Tagetes patula). With germander (Teucrium fruticans), growth was depressed with mycorrhizal inoculation in the medium composed of 60% coir. Growth of lavender (Lavandula augustifolia) was depressed in all coir-amended media, with or without AM inoculation, compared to the nonamended control. These results confirm previous reports of varied response of plant species to coir, and indicate the lack of any detrimental effects of coir on mycorrhiza formation.

Time course of N 2 fixation and growth of chickpea

The 15N isotopic dilution technique was used to assess N2 fixation in desi chickpea (Cicer arientinum L.) cv. Myles at different growth stages as influenced by inoculation method. In this growth chamber study, no significant differences in nodule dry weight, amount of N2 fixed and plant dry matter were observed between seed inoculation with seed-applied peat inoculant and soil-applied granular inoculant placed 2.5 cm below the seed. However, seed inoculation with liquid inoculant was inferior to the seed-applied peat or the granular inoculant for all parameters measured at all sampling dates. The seed-applied peat and granular inoculant treatments fixed 4.8 and 4.1 mg N plant–1, respectively, by the late vegetative stage, and reached a maximum of 20.6 and 25.6 mg N plant–1, respectively, by the late pod-filling stage. These values accounted for 30.5% and 34.9% of the total plant N for the peat and granular inoculant, respectively, by late pod-filling. For the liquid inoculant treatment, the amount of N2 fixed increased from 2.3 mg N plant–1 by the late vegetative stage to a maximum of 9.6 mg N plant–1 which was 22.2% of total plant N by the mid pod-filling stage. The highest daily N2 fixation rate for the peat and granular inoculant was 0.9 mg N plant–1 and occurred between flowering and early pod-filling, whereas that for the liquid occurred between early and mid pod-filling stages (0.23 mg N plant–1). After the mid pod-filling stage, little or no N2 was fixed in all treatments. Plant dry matter increased from the late vegetative stage to physiological maturity but the greatest dry matter accumulation occurred between the late vegetative and early pod-filling stages in all treatments.

Effects of Sphagnum peat and copper sulfate on productivity of a Ferro-Humic Podzol

Sphagnum peat is an abundant resource in the Quebec boreal zone and can be used to improve water retention in sandy soils of low productivity. Our objective was to select a peat application rate suitable for growing potato (Solanum tuberosum L. 'Superior') and barley (Hordeum vulgare L. 'Chapais') on a ferro-humic podzol. The experiment was conducted in Mistassini, Quebec, from 1994 to 1997. Organic matter content (OMC) of a Parent loamy sand was 2.7–2.9% initially. Peat was applied to small plots in a 2-yr potato and 2-yr barley rotation at rates of 0 (control), 29, 48 and 68 t ha−1 on a dry weight basis. A cupric fertilizer trial (0 vs. 2.2 kg Cu ha−1) was combined with the peat treatments. A yearly potato–barley rotation was also established in a nearby field receiving 25 t peat ha−1. The arable layer of peat-amended soils was stratified into a 5.3- to 14.8-cm thick upper layer (A1) down to the limit of peat incorporation, and an underlying layer (A2), averaging 15 cm in thickness, keeping the original soil properties. The highest tuber yield, but reduced tuber specific gravity, were obtained with the 48 t ha−1 treatment compared with the control and the 29 t ha−1 treatments. Peat rates excceeding 29 t ha−1 reduced yield and quality of the barley crop. The Cu concentration in barley and potato diagnostic tissues decreased as peat rate increased. Copper was needed to counteract the detrimental effects of peat amendments on maturation, yield and quality of barley. At field scale, peat increased the lower limit of soil water content for starting irrigation from 0.12 m3m−3 in the control to 0.15 m3m−3 in the peat-amended soil. Irrigation rate should be augmented at each passage, and frequency of waterings diminished, in peat-amended soils compared with the control, due to increased water storage capacity. Peat improved the productivity of the sandy soil up to 4–5% OMC, but could induce Cu shortage in barley. Key words: Soil water, potato, Solanum tuberosum L., barley, Hordeum vulgare L.

Acidifying peat as an aid to the reconstruction of lowland heath on arable soil: a field experiment

1. The potential of naturally pyritic peat as a soil amendment for the reconstruction of lowland heath on land with a long history of arable cultivation was investigated in a factorial, field experiment. Peat was incorporated to a depth of 0·5 m at 50% and 75% by volume; a third treatment had a 0·1‐m blanket of peat overlaying a 75% mixture, and unamended soil was the control. Half of each treatment plot was sown with forage‐harvested brashings of Calluna vulgaris and the other half with acidophilic grasses (Agrostis capillaris, Festuca ovina, Deschampsia flexuosa). 2. Peat‐treated plots acidified rapidly to pH 2·5–3·5, depending on the proportion of peat, whereas the control soil remained at pH 6·0–7·0. After 5 years the pH of the treated plots had risen slightly and was stable at between 3 and 4. There was considerable spatial variability in all peat incorporation treatments. 3. High densities of C. vulgaris established in the first summer on both peat mixtures, especially the 50% peat, but densities were very low on the peat blanket and control soil. The growth of the largest individual plants was as good on the peat blanket as on the mixtures but was generally poor on the control soil. However, the development of cover was much more rapid on both mixtures (approaching 50% after 5 years) than on either the peat blanket or control soils. Calluna vulgaris flowered well on all peat treatments from the second summer (1994). Various measures of performance of C. vulgaris, considered across treatments, showed optima at around pH 3–4. 4. On the grass subplots, Agrostis capillaris became dominant, reaching very high cover on 50% peat and control soil. Festuca ovina occupied the less acid areas within treatments, and Deschampsia flexuosa increased steadily in cover on particularly acid areas (10% cover by 1996 on the peat blanket). 5. Pioneer annual weeds were replaced by persistent perennial weeds, particularly in C. vulgaris subplots. Their establishment was probably facilitated by lack of competition, together with fertile pockets and channels resulting from imperfect mixing of the peat. Regular cutting above the C. vulgaris canopy was necessary to control the spread of Cirsium arvense, Agrostis gigantea, Rubus fruticosus, Urtica dioica and Betula pendula. Rubus fruticosus and U. dioica invaded even the extremely acid peat blanket. 6. Pyritic peat can be used to create soil conditions suitable for the rapid establishment of heathland species. Grazing, cutting and ‘weed‐wiped’ herbicides would probably be necessary to control persistent, acid‐tolerant weeds in the management of vegetational development.

Response of Soil Aggregate Stability to Manure Amendments in the Ultuna Long‐Term Soil Organic Matter Experiment

AbstractThe present paper deals with the long‐term effects of bare fallow and organic treatments on soil aggregate stability. Soil samples were collected from plots of the long‐term soil organic matter experiment in Ultuna/Sweden, which is already running for 38 years.Soil aggregate stability (SAS) showed a clear response to soil management. SAS increased in following order: bare fa llow &lt; no‐N &lt; green manure &lt; peat ≤ farmyard manure. Humus contents of the plots had a significant impact on S AS. Increasing Corg− contents generally enhanced aggregation. However, the unfavourably high C/N ratio of peat treatments and the resulting small size of microbial biomass led to a distinctly lower positive influence of accumu lated soil organic matter in case of peat additions.

ESTABLISHMENT OF `GULFCOAST' SOUTHERN HIGHBUSH BLUEBERRY

In a 1989 field study, `Gulfcoast' southern highbush blueberry plants were subjected to irrigation [8 liters per week (low) and 30 liters per week (high)], mulching (none and 15 cm height), row height (level and raised 10-15 cm), and soil incorporated peat (none and 15 liters in each planting hole) treatments at establishment. Plants were grown on a well-drained fine sandy loam soil that contained &lt; 1.0% organic matter. Plant volume was increased by either mulching, high irrigation, incorporated peat moss or level beds. Fruit yields were not significantly affected by irrigation levels but were highest with either mulching, level beds or incorporated peat moss. The bed height X mulching interaction indicated that mulching increased yield more with level beds than with raised beds. Plants grown with the combination of mulching, level beds, incorporated peat moss, and high irrigation levels yielded 1.1 kg per plant or approximately 10 times more than plants grown without mulch, with raised beds, without peat moss, and with the low rates of irrigation. Of the 4 establishment practices evaluated, mulching had the greatest influence on plant growth and fruiting.

Effect of organic matter on splash detachment and the processes involved

AbstractThe influence of organic matter on splash detachment was investigated using soils with grass and peat treatments. The relationship between organic matter and aggregate stability to water disruption was positive for soils with grass treatment while it was negative for those with peat treatment. Organic matter from both treatments, however, reduced splash detachment by rainfall. Soils with grass did this by increasing aggregate stability while peat acted as a mulch on the soil surface. This implies that though organic matter always reduces splash detachment, different processes may be involved, depending on the form of the organic material.Because of the different processes involved, both negative and positive relationships between splash detachment and aggregate stability as reported in literature were obtained for the soils with grass and peat respectively.

EFFECT OF LONG-TERM ANNUAL ADDITIONS OF VARIOUS ORGANIC AMENDMENTS ON THE ORGANIC MATTER OF A CLAY AND A SAND

Annual additions of green rye, straw, alfalfa, leaves, peat, muck and manure to an Uplands sand and a Rideau clay soil under field conditions were made for a 20-year period. With the Rideau clay there was a loss of organic matter on the control and rye plots; most of the loss with the control plot was in the first 10 years. The additions of straw, alfalfa, leaves and manure maintained the carbon level. Only the peat and muck treatments increased the organic matter, all the increase taking place in the first 10 years. With the Uplands sand the carbon decreased on the control, but all other treatments increased the carbon content. These effects were largest with the peat and muck and took place in the first 10 years.In general, the pyrophosphate solubility and acriflavine adsorption capacity of the soil organic matter were related to their carbon contents. Dehydrogenase activity did not appear to be related to organic matter. Oxygen uptake, in a Warburg respirometer, was lowest with the samples from the control plots from both soils. After drying and rewetting of the soils, a second Warburg test showed that the oxygen uptake was at a lower level.