Schils R.L.,Wageningen University |
Postma R.,Nutrient Management Institute |
van Rotterdam D.,Nutrient Management Institute |
Zwart K.B.,Wageningen University
Journal of the Science of Food and Agriculture | Year: 2015
BACKGROUND: In regions with intensive livestock systems, the processing of manure into liquid mineral concentrates is seen as an option to increase the nutrient use efficiency of manures. The agricultural sector anticipates that these products may in future be regarded as regular mineral fertilisers. We assessed the agronomic suitability and impact on greenhouse gas (GHG) and ammonia emissions of using liquid mineral concentrates on arable farms. RESULTS: The phosphate requirements on arable farms were largely met by raw pig slurry, given its large regional availability. After the initial nutrient input by means of pig slurry, the nitrogen/phosphate ratio of the remaining nutrient crop requirements determined the additional amount of liquid mineral concentrates that can be used. For sandy soils, liquid mineral concentrates could supply 50% of the nitrogen requirement, whereas for clay soils the concentrates did not meet the required nitrogen/phosphate ratio. The total GHG emissions per kg of plant available nitrogen ranged from -65 to 33 kg CO2-equivalents. It increased in the order digestates
Van Eekeren N.,Louis Bolk Institute |
de Boer H.,Wageningen University |
Hanegraaf M.,Nutrient Management Institute |
Bokhorst J.,Louis Bolk Institute |
And 5 more authors.
Soil Biology and Biochemistry | Year: 2010
Biotic soil parameters have so far seldom played a role in practical soil assessment and management of grasslands. However, the ongoing reduction of external inputs in agriculture would imply an increasing reliance on ecosystem self-regulating processes. Since soil biota play an important role in these processes and in the provision of ecosystem services, biological soil parameters should be an integral part of soil assessment. The general objective of the current study is to investigate to what extent biotic soil parameters provide additional value in soil quality assessment of grassland on sandy soils. We measured abiotic and biotic soil parameters together with process parameters underlying ecosystem services in 20 permanent production grasslands. Cross-validated stepwise regression was used to identify abiotic and biotic soil parameters that explained the soil ecosystem services soil structure maintenance, water regulation, supply of nutrients, and grassland production, respectively.Process parameters underlying the ecosystem service soil structure maintenance such as bulk density and the percentage of sub-angular blocky elements were mainly influenced by SOM and its qualities. The correlations between penetration resistance at 0-10cm and the percentage of soil crumbs with earthworms suggested a relationship to earthworm activity. Parameters underlying the service of water regulation showed no clear relationship to biotic soil parameters. Water infiltration rate in the field was explained by the penetration resistance at 10-20cm. Process parameters underlying the service of nutrients' supply such as the potentially mineralizable C and N were mainly determined by soil total N. The potential C and N mineralization were more related to biotic soil parameters, whereby each parameter was the other's antithesis. The grassland production without N fertilization viz. the nitrogen supply capacity of the soil measured as N yield, was mainly explained by soil organic matter (SOM) and soil moisture, and to a lesser extent by soil total N. One gram of SOM per kg of dry soil corresponded to 3.21kgNyieldha-1, on top of a constant of 15.4kgNha-1. The currently applied calculations in the Dutch grassland fertilization recommendation, underestimated in 85% of the production grasslands, the measured nitrogen supply capacity of the soil by on average 42kgNha-1 (31%). This legitimizes additional research to improve the currently applied recommendations for sandy soils. The response of N yield to N fertilization ranged from 35 to 102%. This wide range emphasizes the importance of a better recommendation base to target N fertilizer. The response of N yield to N fertilization was predicted by the total number of enchytraeids, the underlying mechanism of which needs further investigation on different soil types. This knowledge can be important for the optimal use of fertilizer and its consequences for environmental quality. © 2010 Elsevier Ltd.
van Rotterdam A.M.D.,Nutrient Management Institute |
van Rotterdam A.M.D.,Wageningen University |
Bussink D.W.,Nutrient Management Institute |
Temminghoff E.J.M.,Wageningen University |
van Riemsdijk W.H.,Wageningen University
Geoderma | Year: 2012
In agriculture there is a growing need to use phosphorus (P) fertilizer more efficiently because of P related environmental problems and diminishing P reserves. A key factor to achieve this is an accurate prediction of the P supply potential of a soil. To improve the choice of soil tests and interpretation of the corresponding results a new methodology is proposed. The methodology is derived based on the continuous removal of P from soils using an artificial P sink (Fe oxide-impregnated paper) and linking the results to standard soil tests. To achieve this, the desorption results are modeled based on the adsorption characteristics of the P sink and a soil specific Langmuir desorption isotherm in which the parameters are calculated a priori from standard soil tests. To be able to make any prediction of the P supply potential a minimum of two parameters is needed: a measure for the reversibly adsorbed P (Q) and for the P concentration in solution (C). The best prediction is obtained when Q was approximated by P-Olsen, followed by PAL and Pox. The measure for C is an indication of the rate with which P can be removed from the soil and is approximated by P-CaCl 2. The ratio Q over C is an indication of the capacity of the soil to buffer C, and thus the capacity to maintain the flux from the soil to a sink. The accuracy of this prediction increases for soils with high buffer power, i.e. with low P saturation of the reactive surface area associated with the readily desorbable P. In this case the Langmuir isotherm is linear. To increase the accuracy of this prediction for soils that do not have a high buffer power, and the Langmuir isotherm is thus nonlinear, a measure for the reactive surface area (e.g. Fe ox and Al ox) of the soil must also be taken into account. In addition, to be able to extend the prediction of the soil P supply potential to an amount of P exceeding the amount of readily desorbable P, a measure for the total desorbable P content must be included (e.g. P ox). This total desorbable P content dictates the level at which C is highly buffered once the reversibly adsorbed P has been depleted.The methodology was verified in pot- and field experiments. Implementation of the methodology based on two parameters in a Dutch routine soil laboratory has resulted in a more accurate P fertilizer recommendation for grassland. © 2012 Elsevier B.V.