Soil carbon sequestration in Switzerland - the DOK trial

Organic systems, by closing nutrient cycles and making more efficient use of local (on-farm) resources, can contribute to mitigating climate change1. This is due to the fact that certain farming practices result in storage of carbon (C) in the soil (sequestration), thereby effectively reducing the amount of CO2 in the atmosphere. The DOK trial, a research project on the mitigation potential of Organic Agriculture has demonstrated this

Lucerne (Medicago sativa) or grass-clover as cut-and-carry fertilizers in organic agriculture

On-farm nitrogen fixation is a driving force in organic agriculture. The efficiency with which this nitrogen is used can be increased by using lucerne (Medicago sativa) or grass-clover directly as sources of fertilizer on arable land: cut-and-carry fertilizers. In two arable crops, the use of lucerne and grass-clover as fertilizers was compared with the use of poultry manure and slurry. The nitrogen-use efficiency at crop level was comparable or better for the cut-andcarry fertilizers as compared to the animal manures. The relative P and K content of these fertilizers came closer to the crop demand than that of the poultry manure. Crop yields were comparable or better when using lucerne or grass-clover as fertilizer. It is concluded that cutand-carry fertilizers are a serious alternative for manure as part of an overall farm soil fertility strategy

Aanpassing voer vergemakkelijkt de toepassing van pluimveemest: Eerste resultaten van pilotstudies naar effect van biologische fytase positief

In Nederland zijn er nu ruim 1 miljoen biologische legkippen die jaarlijks bijna 300 miljoen eieren produceren maar ook 25.000 ton mest. De meeste legkippenhouders hebben zelf weinig grond en moeten de mest afvoeren. Het project ‘Kippenmest en Kringloop’ streeft er naar deze mest zo goed mogelijk in te zetten en te benutten binnen de biologische landbouw. Om de mest aantrekkelijker te maken voor bijvoorbeeld de akkerbouw is het belangrijk dat de mestkwaliteit en daarbij met name de verhouding tussen stikstof en fosfaat verbetert. In 2009 en 2010 zijn pilots uitgevoerd om het effect van aanpassingen in het kippenvoer op de mestkwaliteit te onderzoeken

Effects Of Grass-Clover Silage Quality And Application Rate On Organic Potato Performance

Most organic farmers use animal manure as a source of crop nutrients. However, recent experiments have revealed that cut-and-carry fertilisers like grass-clover silage may provide a viable alternative. The objective of the current study was to investigate the performance of an organic potato crop on a sandy soil fertilised with grass-clover silages differing in C: N ratio (16, 17, 22 and 24) and nitrogen application rate (0, 57, 113 and 170 kg N ha-1). The total tuber yield was highest for the silage with a C: N ratio of 16 (44 Mg ha-1). However, the yield difference with the silage having a C: N ratio of 24 was not more than 10% (40 Mg ha-1). In terms of N application rate, there was a linear increase in yield with N rate while the share of marketable potatoes also improved with N-rate. In the non-amended control, the potato yield was 30.5 Mg/ha, whereas with 170 kg N ha-1 this was 47.5 Mg/ha. The agronomic nitrogen efficiency (ANE; kg tubers per kg applied N) was not affected by either the C: N ratio or the N application rate. However, ANE values tended to be highest for the C: N ratio of 16 (115 kg tubers/kg N) and an application rate of 170 kg N ha-1 (100 kg tubers/kg N). Overall, crop performance and N-utilisation were more than adequate which underlines that grass-clover silage can be considered as a potential substitute for animal manure sources

Genotype x management interaction for nutrient use efficiency (NUE) of maize varieties tested under different tillage and fertilization regimes

Most varieties have been selected under high input conditions, including seed treatment, herbicide applications, as well as optimal levels of fast releasing fertilizers. Under organic farming nutrient release is dependent on the temperature and biological activity of the soil and its interaction with the declining residues from previous crops and applied quantity of farmyard manure. As a consequence it is not always possible to match nutrient release with crop demand over time. This effect is even more severe under conservation tillage. To promote conservation tillage in organic farming, it is necessary to identify cultivars that show high nutrient use efficiency (NUE) under these conditions. While there is substantial evidence that breeding for low N input conditions selection is more efficient under severe N stress than under high input conditions only few studies have been conducted to demonstrate the difference in selection gain between organic and inorganic fertilization or between different soil tillage management. The objectives of the study were (i) to quantify the NUE of maize (Zea mays L.) genotypes under different tillage regimes and fertilization levels, (ii) to compare the effect of slow releasing organic versus inorganic fertilizer, and (iii) determine genotype x management interaction

Influence of reduced tillage and fertilisation regime on soil quality indicators in an organic potato production system

The aim of this study was to assess the short-term effects of tillage practice (reduced tillage – RT; standard tillage – ST) and fertilisation regime (solid cattle manure – SCM; lucerne pellets – LP; grass/clover silage – GCS) on soil quality indicators in an organic potato (Solanum tuberosum L.) production system. Use of RT enhanced the biomass and number of earthworms compared with ST. Concentrations of soil mineral N ((Formula presented.) and (Formula presented.)) showed similar decreasing patterns over time across both tillage systems during the potato production period. However, soil mineral N was overall higher in the 0–15 cm soil layer for RT and in the 15–30 cm layer for ST. Soil bulk density was higher for RT than ST at 1, 4 and 7 weeks after planting, while a linear reverse correlation was found between soil bulk density and tuber yield. Although both soil temperature and soil moisture content were not found to be greatly affected by tillage practice, net soil N mineralisation was estimated to be 65 kg N ha−1 greater under ST than RT for the potato production period. The application of LP and GCS resulted in higher mid- and end-season soil mineral N concentrations and crop N accumulation at harvest compared to SCM. During initial adaptation to reduced tillage practices in organic potato systems, farmers need to carefully weigh potential conflicts between initial yield reductions and soil conservation goals

Influence of reduced tillage and fertilization regime on crop performance and nitrogen utilization of organic potato

The majority of Dutch farmers perceive that mouldboard ploughing prior to potato planting is necessary, despite its negative impacts on inherent soil fertility and soil structure. An innovative agronomic practice in Dutch organic agriculture is the use of cut-and-carry fertilizers with which above-ground biomass of crops with high nitrogen content (e.g. grass/clover) is harvested and transferred to other fields as plant-based fertilizers. The objective of this study was to investigate the interactive effects of two tillage systems (reduced tillage (RT), standard tillage (ST)) and three organic fertilizer amendments (solid cattle manure (SCM), lucerne pellets (LP), grass/clover silage (GCS)) on crop performance and nitrogen utilization of organic potato. Use of RT decreased tuber yield by 13.4 % compared to ST due to lower average tuber size which was related to higher soil bulk density and increased vulnerability to drought stress during tuber bulking. On the other hand, use of RT positively affected nitrogen utilization and tuber quality in terms of specific gravity, dry matter and starch contents. However, the price premium associated with enhanced tuber quality may not offset the observed yield gap between RT and ST. Plant-based fertilizers enhanced nitrogen utilization in terms of apparent nitrogen recovery compared to animal-based. Although use of LP resulted in the highest yield for both tillage systems, its high price may be cost-inhibitive. An integrated approach taking into account N release patterns, environmental conditions, final yields, and production costs is needed in order to optimize resource use efficiency and overall profitability for farmers.ISSN:1879-4238ISSN:1879-424

Influence of reduced tillage on earthworm and microbial communities under organic arable farming

Although reduced tillage is an agricultural practice reported to decrease soil erosion and external inputs while enhancing soil fertility it has still rarely been adopted by European organic farmers. The objective of this study was to assess the long-term interactive effects of tillage [conventional (CT) versus reduced (RT)] and fertilization [slurry (S) versus composted manure/slurry (MCS)] on earthworms and microbial communities in a clay soil under spelt in an organic 6-year crop rotation. Earthworm populations (species, density and biomass, cocoons) were investigated by handsorting the soil nine years after initial implementation of the treatments. Soil microbial carbon (Cmic) and nitrogen (Nmic) were measured by chloroform-fumigation extraction and a simplified phospholipid fatty acid (PLFA) analysis was used to separate for populations of bacteria, fungi and protozoa. Total earthworm density was significantly increased in RT plots mainly being related to increased numbers of juveniles. Moreover, we found five times more cocoons with RT. Species richness was not affected by the treatments, but tillage treatments have differentially altered populations on species-level. In addition, cluster analysis on community level revealed two distinct groups of plots in relation to tillage treatments. In RT plots Cmic increased in the 0-10 cm and 10-20 cm soil layers, while PLFA concentrations indicative of Gram-negative bacteria, fungi and protozoa only increased in the topsoil. Lower bacteria-to-fungi ratios in the upper soil layer of RT plots indicated a shift to fungalbased decomposition of organic matter whereas a higher Cmic-to-Corg ratio pointed towards enhanced substrate availability. Slurry application decreased microbial biomass and enhanced density of juvenile anecic earthworms but overall fertilization effect was weak and no interactions with tillage were found. In conclusion, tillage is a major driver in altering communities of earthworms and microorganisms in arable soils. The use of reduced tillage provides an approach for eco-intensification by enhancing inherent soil biota functions under organic arable farming