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1.
Five soil treatments in a 4-year-old clearcut in southern Sweden affected biomass increase and net nitrogen uptake by planted Norway spruce (Picea abies (L.) Karst.) seedlings through their on net mineralisation and root growth. The patch soil treatments studied were: (i) soil inversion in an old clearcut; (ii) mineral soil from the clearcut remaining, (iii) mineral soil from the clearcut with fertiliser application during the first season; (iv) mineral soil from a nearby uncut forest replacing the clearcut mineral soil; and (v) an untreated control. Growth increased in seedlings in treatments (i) and (iii), but growth in soil treatments with humus removal was not better than that of seedlings in untreated soil. High N uptake early in the first growing season resulted in increased growth during this season in contrast to late N uptake that resulted in a high N concentration in the seedlings after the first growing season. This in turn led to a high growth rate during the next growing season. Generally, both root growth and net N mineralisation were positively correlated to N uptake in the soil treatments. Therefore, a combination of low net N mineralisation and poor root growth as a result of high soil density appears to explain the low N uptake in seedlings in undisturbed soil. The importance of competition with field vegetation for N and water was not clear. Net mineralisation was larger in soil treatments where the humus layer was retained than where it was removed. Net N mineralisation in soil from old clearcuts was the same as in soil from fresh clearcuts. 相似文献
2.
Haydon S. Jones Peter N. BeetsMark O. Kimberley Loretta G. Garrett 《Forest Ecology and Management》2011,262(3):339-347
Growing interest in the use of planted forests for bioenergy production could lead to an increase in the quantities of harvest residues extracted. We analysed the change in C and N stocks in the forest floor (LFH horizon) and C and N concentrations in the mineral soil (to a depth of 0.3 m) between pre-harvest and mid-rotation (stand age 15 years) measurements at a trial site situated in a Pinus radiata plantation forest in the central North Island, New Zealand. The impacts of three harvest residue management treatments: residue plus forest floor removal (FF), residue removal (whole-tree harvesting; WT), and residue retention (stem-only harvesting; SO) were investigated with and without the mean annual application of 190 kg N ha−1 year−1 of urea-N fertiliser (plus minor additions of P, B and Mg). Stocks of C and N in the forest floor were significantly decreased under FF and WT treatments whereas C stocks and mass of the forest floor were significantly increased under the SO treatment over the 15-year period. Averaged across all harvesting treatments, fertilisation prevented the significant declines in mass and C and N stocks of the forest floor which occurred in unfertilised plots. The C:N ratio of the top 0.1 m of mineral soil was significantly increased under the FF treatment corresponding to a significant reduction in N concentration over the period. However, averaged across all harvesting treatments, fertilisation prevented the significant increase in C:N ratio of the top 0.1 m of mineral soil and significantly decreased the C:N ratio of the 0-0.3 m depth range. Results indicate that residue extraction for bioenergy production is likely to reduce C and N stocks in the forest floor through to mid-rotation and possibly beyond unless fertiliser is applied. Forest floors should be retained to avoid adverse impacts on topsoil fertility (i.e., increased C:N ratio). Based on the rate of recovery of the forest floor under the FF treatment, stocks of C and N in the forest floor were projected to reach pre-harvest levels at stand age 18-20. While adverse effects of residue extraction may be mitigated by the application of urea-N fertiliser, it should be noted that, in this experiment, fertiliser was applied at a high rate. Assessment of the sustainability of harvest residue extraction over multiple rotations will require long-term monitoring. 相似文献
3.
C.G. Sorensen L. Pesonen P. Suomi P. Bildsøe 《Computers and Electronics in Agriculture》2010,73(1):44-55
Agriculture and farmers face a great challenge in effectively manage information both internally and externally in order to improve the economic and operational efficiency of operations, reduce environmental impact and comply with various documentation requirements. As a part of meeting this challenge, the flow of information between decisions processes defined as realizing a decision must be analyzed and modelled as a prerequisite for the subsequent design, construction and implementation of information systems.This paper defines the actors, their role and communication specifics associated with the various decision and control processes in farmers’ information management. Core-task analysis and core task demands from earlier research are utilised as premises for the modelling of information flow from the farmers’ point of view. A user-friendly generic FMIS design reference model is the primary objective for the study in which planning, execution and evaluation measures have been incorporated.A user-centric approach to model the information flows for targeted field operations is presented. The information models are centred around the farmer as the principal decision maker and involves external entities as well as mobile unit entities as the main information producers. This is a detailed approach to information modelling that will enable the generation of a Farm Management Information System in crop production. 相似文献
4.
Pine plantations on selected sites in the extensive zone of degraded oak coppice of northern Greece are deemed necessary for increasing wood production in the area and suitable site preparation may accelerate early tree growth. Seven site preparation treatments including raking (R), with sub-soiling (RS), disc harrowing (RD), tine ploughing (RT) and their combinations (RSD), (RDT) and (RSDT) were compared for the establishment of black pine (Pinus nigra Arn) in an oak coppice site, of conglomerate parent material at Anthrakia, northern Greece. The randomised blocks trial of three replications and 110 trees per treatment, half of which were fertilised with 150 g NPK per plant, was assessed at the age of 15 years for diameter, dominant tree height and survival. There was no significant difference between the treatments in any of the traits examined, nor did the fertilisation had any effect. Only the fertiliser × treatment interaction was found significant at p<0.001 for dominant height, accounting for 37% of the observed variation in this trait. The lack of response to site preparation treatments may be attributed to the hard Bt3 clay horizon, extending beyond cultivation depth (50 cm), that prevents the roots penetration into deeper moist soil layers. The F × T interaction, where the combination of (RSDT) treatment and fertiliser was found to accelerate tree height growth in relation to the same treatment without fertiliser, indicates that thorough soil cultivation is needed for fertilisation to be effective in such sites. 相似文献
5.
Long-term effects of fertilisation regime on earthworm abundance in a semi-natural grassland area 总被引：1，自引：0，他引：1
Environmental protection organisations involved in farmland-bird conservation promote the use of organic fertilisers, especially farmyard manure, to enhance the availability of earthworms, which are an important prey for farmland-birds. We studied changes in earthworm numbers in a field experiment on a semi-natural grassland with three different types of fertilisation; no fertilisation (NF), and application of slurry manure (SM) or farmyard manure (FM). Samples were taken in April, yearly from 1982 to 1990 and in 2005. On average, the SM treatment had a lower (29%) earthworm abundance and a higher mean individual body weight than the FM and NF treatments. No statistically significant differences were observed between the FM and NF treatment. In 2005, earthworm abundance did not differ between the SM and NF treatment. The yearly variation in earthworm numbers and biomass was high, and significantly related to winter coldness. Colder winters resulted in lower earthworm abundances in the next spring. Especially the number of endogeic earthworms varied with winter coldness. The large variation between years stresses the need to be careful with the interpretation of short-term field experiments, or comparisons between areas based on single sampling events. 相似文献
6.
Timo Kautza Frank Ellmer Cristina López-Fando Enn Leedu Wolfgang Köhn 《Archives of Agronomy and Soil Science》2013,59(5):513-520
Soil micro-arthropods play an important role in the nutrient cycle of agro-ecosystems and are considered to have a strong impact on microbial activity. The occurance of soil microarthropods was investigated in the International Organic Long-Term Field Experiment (IOSDV). The investigation took place in the experimental fields of Berlin/Germany, Madrid/Spain and Tartu/Estonia. Field plots "without organic fertisation", "farmyard manure" and "straw-beet-leaves-green manure" without mineral N-fertilisation and with 120kg/ha mineral N-fertilisation respectively have been investigated. Data shows that the effects of organic manure and mineral N-fertilisation are considerably influenced by specific site characteristics. The highest abundances were found in the experimental field of Madrid. In the two nothern sites soil microarthropods were found only in very low quantities. Data indicates that not only organic manure but also mineral N-fertilisation may influence the abundance of soil micro-arthropods positively. 相似文献
7.
The effects of nitrogenous fertilisation on litter fall, FH layer and soil characteristics were investigated in replicated trials in six second rotation New Zealand Pinus radiata plantation forests. Four trial sites also incorporated three different post-harvest organic matter removal treatments. All sites were sampled in early 2002 and 2003. Fertilisation significantly increased the nitrogen content and decreased the carbon:nitrogen ratio of the litter fall. Fertilisation significantly increased the mass of the FH layer in the treatment plots, moisture content in the FH layer, the concentration of nitrogen in the FH layer and the pool of carbon and nitrogen stored in the FH layer. Fertilisation significantly increased the nitrogen concentration of the mineral soil, and decreased the mineral soil carbon:nitrogen ratio and pH. Several significant site × fertilisation interaction terms indicated that variations in the fertilisation regimes and site characteristics substantially influenced the effects of fertilisation. Fertilisation did not significantly decrease the relative differences between the organic matter removal treatments. The significant differences in the litter fall, FH layer and mineral soil characteristics strongly suggest that nitrogenous fertilisation has the capacity to significantly alter the forest floor environment, and may be able to increase carbon storage over the life of the rotation. 相似文献
8.
During 2 years, a melon crop (Cucumis melo L. cv. Sancho) was grown under field conditions to investigate the effects of different nitrogen (N) and irrigation (I) levels on fruit yield, fruit quality, irrigation water use efficiency (IWUE) and nitrogen applied efficiency (NAE). The statistical design was a split-plot with four replications, where irrigation was the main factor of variation and N was the secondary factor. In 2005, irrigation treatments consisted of applying daily a moderate water stress equivalent to 75% of ETc (crop evapotranspiration), a 100% ETc control and an excess irrigation of 125% ETc (designated as I75, I100 and I125), while the N treatments were 30, 85, 112 and 139 kg N ha−1 (designated as N30, N85, N112 and N139). In 2006, both the irrigation and N treatments applied were: 60, 100 and 140% ETc (I60, I100 and I140) and 93, 243 and 393 kg N ha−1 (N93, N243 and N393). Moderate water stress did not reduce melon yield and high IWUE was obtained. Under severe deficit irrigation, the yield was reduced by 22% mainly due to decrease fruit weight. The relative yield (yield/maximum yield) was higher than 95% when the irrigation depth applied was in the range of 87-136% ETc. In 2006, the interaction between irrigation and N was significant for yield, fruit weight and IWUE. The best yield, 41.3 Mg ha−1, was obtained with 100% ETc at N93. The flesh firmness and the placenta and seeds weight increased when the irrigation level was reduced by 60% ETc. The highest NAE was obtained with quantities of water close to 100% ETc and increased as the N level was reduced. The highest IWUE was obtained with applications close to 90 kg N ha−1. The I243 and I393 treatments produced inferior fruits due to higher skin ratios and lower flesh ratios. These results suggest that it is possible to apply moderate deficit irrigation, around 90% ETc, and reduce nitrogen input to 90 kg ha−1 without lessening quality and yields. 相似文献
9.
Yutong Hu Xiaorong Wei Xu Chen Jing Zhao 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2016,66(5):406-416
Wheat yield is influenced by fertilisation, precipitation and variety, among other factors. There is limited research identifying the most important factors affecting wheat yield and assessing their relative importance in the long run. In this study, we evaluated the contribution of fertilisation, precipitation and variety to wheat yield using a long-term field experiment (1984–2014) on the semiarid Loess Plateau in China. The experiment consisted of six treatments: fertilisation with nitrogen (N), phosphorus (P), manure (M), NP, NPM, and a control without fertilisation. We monitored the yield of three varieties of winter wheat over time and assessed the changes in grain yield, soil properties, fertiliser-contribution rate (FCR) and precipitation-use efficiency (PUE) with different fertilisation treatments and precipitation patterns. Stepwise multiple linear regression was used to identify the most important factors affecting wheat yield and examine their relative importance. The results showed that fallow-season precipitation and annual precipitation (AnP) positively correlated with wheat yield in the N, M, NP, and NPM treatments. The amount of fertilisation, AnP, and monthly precipitation of February and September were included in the linear regression model; however, the influence of variety on yield could be ignored. With 30 years of fertilisation, soil organic matter, total nitrogen, and available potassium levels with NPM was higher than the control by 70.6%, 70.5%, and 319.2%, respectively. Yield, FCR, and PUE with M increased annually at rates of 89?kg?ha?1?y?1, 1.47?kg?kg?1?y?1, and 0.13?kg?mm?1?y?1, respectively. The yields and FCR, but not PUE, of all fertilised treatments were higher in wet than normal and dry years. The FCR with P was negative in all the three precipitation patterns. This study has implications for maximising the long-term winter yield with various factors in the rain-fed winter wheat cropping system of the Loess Plateau. 相似文献
10.
Dehesa ecosystems are open woodlands with scattered oak trees as their main component. As a result of differing land-uses, the structure of vegetation found within dehesas varies between: (i) oak trees and intercropped cereals (cropped), (ii) oak trees and native grass vegetation (grazed), and (iii) oak trees with abundant understorey shrubs (encroached). The aim of this study is to investigate whether land-use influences the water dynamics of dehesas by measuring available soil water content (AWC) in the upper 250 cm of the soil at different distances from tree trunks (maximum 30 m) at four Quercus ilex dehesas in Central–Western Spain. The technique used was Time Domain Reflectometry and the study was undertaken between May of 2002 and December of 2005. Leaf water potential (Ψ) was also measured on trees at one site by mean of a pressure chamber. Within the upper meter of the soil, it appears that trees, grasses and shrubs extracted soil water resources in a similar way from both beneath and beyond the tree canopy. However, encroached plots in general showed lower average AWC values than cropped or grazed plots (3.7, 5.6, and 6.2% in encroached, cropped and grazed, respectively). Cereal crops do not compete more strongly than grasses with trees for available soil water resources. The similar Ψ values found at cropped and grazed plots supported these results. From our results, it could be hypothesized that ploughed dehesas could facilitate soil re-watering in the plots with pronounced slopes. The decrease of AWC values at encroached plots with respect to the cropped and grazed plots was found mostly beyond the tree trunk at deeper soil layers, indicating that shrubs use water partly not accessible to trees. The presence of an understory of shrubs seems to have slightly increased the water constraints on trees during the summer period (Ψd values of − 0.5, − 0.5, and − 0.8 MPa in cropped, grazed, and encroached plots, respectively). In cropped and grazed plots, an important amount of water seems to have remained unused for trees and grasses. 相似文献