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Chicken manure is a nutrient-rich fertilizer that ought to be applied in moderate doses, which is difficult in practice. Composted chicken manure may be particularly suited for organic vegetable production. Chicken manure is less attractive for application on soils rich in available phosphorus (P) due to its low nitrogen (N)/P ratio. Combining chicken manure and a carbon-rich feedstock for co-composting or temporary storage may overcome these disadvantages and may reduce nutrient and particularly N losses during storage and after application. Goat manure from a deep litter housing system has a high carbon (C)/N ratio and its decomposition can be enhanced by mixing the stockpiled material several times. The microbial decomposition process will probably favour nutrient availability after field application. The heating in the stockpile may also counteract the survival of parasites and pathogenic bacteria. Our objective was to evaluate the fertilization value of compost and manure of different quality using a dosage as limited by the future P input standard of 55 kg ha-1 year-1, for vegetables.
2. Materials & Methods A field trial with a leek crop (Allium ampeloprasum L. var. porrum) was set up in 2011 to assess the N availability from ten different fertilization treatments. The manure products tested were from manure pretreatments. Two chicken manure compost products (ChC1 & ChC2) were selected from two different and intensively monitored compost trials. The first trial focused on several feedstock materials, the second on the amount of chicken manure. Composting was done using a Sandberger Compost Turner® in a windrow composting system. In two other trials chicken manure was stored in a mixture with municipal waste compost (MWC). One mixture was obtained by the use of MWC in the deep litter yard of a chicken stable (ChM-MWC1), another just by artificially mixing manure and compost and storing the mixture (ChM-MWC2). Straw-rich goat manure from a deep litter housing system was mixed twice with the compost turner (TGM). The non-treated goat manure (GM) served as well as fertilization treatment. Four additional treatments were fresh chicken manure (ChM), chicken manure pellets (ChMP), grass clover mowed to use as a fertilizer (MF) and a non-fertilized control (Control). Fertilization was intended to be equal for a P input of 110 kg P2O5 ha-1 (carrots that follow the leek in the rotation in 2012 will not be fertilized). All treatments were replicated 4 times in a completely randomized block design. N availability from the different fertilization products was assessed by determination of (1) the mineral N content in the soil profile (0-60 cm) at several sampling times, (2) the potential N mineralization on summer sampled topsoil (0-25 cm; 3 weeks’ aerobic incubation under standardized circumstances) and (3) the N uptake by the crop (NO3- content in the plant juice, total N leaf content and N yield).
Nitrogen Workshop 2012
3. Results & Discussion With regard to the mineral N content of the soil profile (0-60 cm), significant differences between mean values for the different fertilization treatments were found at the first intermediate sampling time, 6 weeks after planting (Table 1). For 4 out of the 10 fertilization types, marketable yield was lower than that of the control treatment, which we attribute to N-immobilization. Zanen et al. (2008) reported that compost and goat manure seemed to withdraw mineral N from soil for the digestion of the organic matter. In this field trial, a considerable amount of N was taken up from the soil. Soil N availability was quantified and this can enhance N management during the subsequent organic crop production phase (Liu et al., 2011). Marketable crop yield was significantly correlated with soil mineral N in the 0-60 cm layer (R = 0.38, p 0.05), as well as with the total N leaf content (R = 0.59, p 0.001) (Figure 1), both determined 6 weeks after sampling.
4. Conclusion Differences in N availability clearly corresponded to differences in crop performance. Absolute yield differences were relatively small for most of the fertilization treatments. The non-fertilized treatment did not show a real N shortage. Measuring the crop N status may be useful for adjustment of N availability by top mineral N dressing.
References Liu, K., Hammermeister, A. M., Warman, P. R., Drury, C. F. and Martin, R. C. 2011. Assessing soil nitrogen availability in contrasting cropping systems at the end of transition to organic production, Canadian Journal of Soil Science 91, 493-501.
Zanen, M., Koopmans, C., Bokhorst, J. and ter Berg, C. 2008. Special Fertilisation: Successful strategies for sustainable soil management (in Dutch), Louis Bolk Institute publications, no. LD13.
Nitrogen Workshop 2012
N dynamics and priming effect in horticultural fields as influenced by application of mineral fertilizer N a Willekens, K., Vandecasteele, B.a, De Neve, S.b a Institute for Agricultural and Fisheries Research (ILVO), Plant Sciences Unit, Crop Husbandry and Environment, Merelbeke, Belgium b Ghent University, Faculty of Bioscience Engineering, Department of Soil Management, Ghent, Belgium
1. Background & Objectives The eutrophication of surface and ground water from agricultural activities is a major concern for EU policy. In this context, Flanders has to meet the objectives of the European Nitrates Directive.
Overall soil condition, for example C sources, microbiology and soil structure affect N availability.
C and N turnover processes may be affected by the fertilization practice. Having explored data from long-term cropping experiments, Mulvaney et al. (2009) stated that synthetic N depletes soil N. Our objective was to study the effect of applied mineral N on the N mineralization process in cultivated land with a short-term perspective. The research question was if a priming effect would take place, i.e. an enhancement of the net N release from soil organic matter after a mineral N input.
2. Materials & Methods To study the effect of fertilizer N on the N mineralization process, a soil and crop survey was executed in 2009 on 28 fields planted with leek. The sampling was organized both in springtime (April-May), before the fertilization, and in the summer period (mid-July to mid-August), approximately 6 weeks after planting the leek crop. Each time three soil layers were sampled, i.e. 0cm, 30-60cm and 60-90cm and the mineral N content was extracted (1:5 w/v) in a 1 M KCl solution according to ISO 14256-2 and measured with a Foss Fiastar 5000 continuous flow analyser. The plant available N balance was calculated on the basis of a standard N uptake by the young crop of 40 kg ha-1, the mineral N fertilizer input (kg ha-1) and the mineral N content in the profile (kg ha-1, 0-90 cm) at both sampling times. The mineral N fertilizer input comprised N from synthetic or organic fertilization, or both. This N balance result reflects the apparent net N mineralization between both sampling times (Engels and Kuhlmann, 1993). The N balance result was used, together with the mineral N fertilizer input and the total N content of the topsoil layer (%, 0-30 cm), as a variable in a linear regression model for the mineral N profile in summer. This model was set up for 2 distinct field groups, one with a high and the other with a lower level of mineral N fertilizer input. 160 kg N ha-1 was the boundary level for this classification. Summer sampled topsoil (0-30cm) was aerobically incubated during 3 weeks at 15°C and 70% R.H in PVC-tubes (Ø
4.63 cm, filling height 12 cm, bulk density 1.4 g cm-3 and 50% WFPS), by which NH4NO3 (p.a.
35%N) was applied (35.8 mg kg-1 dry soil) and N availability from this synthetic N input was determined.
3. Results & Discussion In the incubation test 18 of the 28 fields showed an enhanced net mineralization rate due to the mineral NH4NO3 input, the so-called priming effect (Figure 1). The availability of applied mineral N was negatively correlated (R = -0.53, p 0.01, n = 28) with the mineral N content in the topsoil layer. The mineral N fertilizer input on the land was positively correlated with the apparent net N mineralization balance result (R = 0.48, p 0.01, n = 28), which may indicate that field application of mineral N resulted in a higher net N mineralization too. Differences in magnitude and significance level of the regression coefficient of the total N content variable in the multilinear regression models for both field groups (Table 1) did confirm the presumed enhancing effect of a mineral N input on the net N mineralization. For the group with the high level of mineral N
fertilizer input, the regression coefficient of total N content is 2.7 times higher than for the other group, although both field groups had a similar total N content. A priming effect in the incubation test was mainly found on fields with a low balance result and vice versa.
Figure 1. Linear fit regression between N availability from NH4NO3 (NavNN) and mineral N content in the topsoil layer (Nmin) (the red horizontal line represents the NH4NO3 fertilizer dose) Table 1.
Regression coefficients and mean values of the variables included in a multilinear regression model for the mineral N profile in summer, for 2 distinct field groups (high and low level of mineral N fertilizer input), **p 0.01, ***p 0.001
4. Conclusion A short term survey of horticultural fields revealed that mineral N input possibly enhances net N mineralization, which is a risk for N losses and soil N depletion.
References Engels T. and Kuhlmann H. 1993. Effect of the Rate of N-Fertilizer on Apparent Net Mineralization of N During and After Cultivation of Cereal and Sugar-Beet Crops, Zeitschrift fur Pflanzenernahrung und Bodenkunde 156, 149-154.
Mulvaney R.L., Khan S.A. and Ellsworth T.R. 2009. Synthetic nitrogen fertilizers deplete soil nitrogen: a global dilemma for sustainable cereal production. Journal of Environmental Quality 38, 2295-2314.
Nitrogen Workshop 2012 N fertiliser replacement value of reversed osmosis liquid fractions on arable land Van Dijk, W.a, Van Geel, W.C.A.a a Applied Plant Research, Wageningen University, Lelystad, The Netherlands
1. Background & Objectives In the Netherlands due to restrictions on nitrogen (N) and phosphorus (P) use the animal manure surplus on a national level will increase the next years. One of the options to control the manure surplus level is manure processing resulting in liquid and solid fractions. Especially liquid fractions resulting from reversed osmosis (RO) separation may be assigned as a fluid mineral fertiliser if N effectiveness and environmental impact are comparable with common mineral fertilisers. Therefore, in 2009 a project was started to assess the N fertilizer replacement value (NFRV) of RO-liquid fractions on arable land as well as grassland. This paper focuses on the results on arable land.
Although assessing NFRV of RO liquid fractions was the main purpose, also the application of the solid fraction was taken into account. The NFRV is defined as the percentage of total N in the product having the same effectiveness as carefully applied mineral N fertilizer.
2. Materials & Methods In 2009 and 2010 two trials were conducted (2+2), one with ware potatoes on a marine clay soil and one with starch potatoes on a sandy soil. In all trials three RO-liquid fractions from different plants and one solid fraction were compared with the commonly used solid N fertilizer calcareous ammonium nitrate (CAN). For all products (liquid and solid fractions, CAN) there were four N application rates (0, 50, 100 and 150 kg N per ha) applied before planting. The liquid fractions were injected in the soil at a depth of 7-10 cm, the solid fraction was surface spread and incorporated within 2-4 hours after spreading. In the trials also the application of liquid fractions after planting (start tuber set) was investigated. This was done at a N rate of 50 kg N per ha for the liquid fractions as well as the reference CAN. All treatments received a base fertilisation of 100 kg N per ha with CAN before planting resulting in a total N rate of 150 kg per ha-1 (60% of recommended level). The RO liquid fraction was injected between the ridges at a depth of 5-6 cm. The total N content and the mineral N fraction (% of total N) of the RO-liquid fractions varied from 4.2-8.7 kg N per ton and 89-95% respectively (Table 1). For the solid fraction values were 13-14 kg N per ton and 42-53% respectively. The supply with other nutrients than N (phosphorus, potassium, sulphur, magnesium) was set equal for all objects by supplementary dressings with mineral fertilisers. NFRV values were derived from differences in N response of the tuber N yield of the liquid and solid fraction compared to CAN by using regression analysis.
3. Results & Discussion For the pre plant application on both locations at all N rates marketable yield and tuber N yield on the RO liquid fractions plots were lower than on the CAN plots (data not shown). For the marketable yield this was only significant for the clay soil location in 2009, for the N yield effects were significant for both clay soil trials. For the sandy soil locations effects were not significant.
The differences in effects of the three RO liquid fractions were small and not significant. The zero
Nitrogen Workshop 2012
control for the liquid fractions did not differ significantly from the zero-control for CAN indicating that negative machine effects did not occur. For the post plant applications in 2009, marketable yield and tuber N yield were lower for the liquid fractions plots than for the CAN plots (significant for the marketable yield on the clay soil and significant for the N yield at both locations). In 2010 no significant differences were observed.