Leguminous service crops in cereal production at high latitudes : provision of ecosystem services and disservices from a novel intercropping system

Service crops, crops grown to provide services such as soil protection, weed control, or nutrient capture and provision, can reduce the need for mineral fertilisers and intensive weed control. However, high biomass production is necessary in order for these services to be provided. This can be difficult to achieve at high latitudes (e.g. Sweden), where growing conditions are poor after main crop harvest, when service crops are usually sown. The aim of this thesis was to increase the understanding of service crop species choice and management on service and disservice delivery. Leguminous service crops were sown into oats in spring/early summer for early establishment of the service crop, and terminated in the following spring in winter wheat. The results showed that species sown at the same time as oats, rather than one month later, and which survived oat harvest and cold temperatures in winter, were best at suppressing weeds and increasing winter wheat yields, although they often also reduced oat yield in the establishment year. Presence of a productive service crop (>0.2 t dry weight (DW) per ha) reduced the occurrence of competitive-stress tolerant weed species, in favour of ruderal species, in the oat row and in combination with oat biomass >8 t DW ha-1 the occurrence of competitive perennial species was reduced. Modelling the system using APSIM NG revealed that the service crops mainly provided positive effects on the cropping system, in terms of increased winter wheat yield, increased soil carbon input and reduced losses of nitrogen and water during most of the study period. Drawbacks were reduced oat yield and increased nitrogen losses from winter wheat and in the fallow period after winter wheat. I conclude that the studied intercropping system has potential to provide services and reduce disservices, but that the system needs improvement. These improvements are mainly to ensure even establishment and good termination of the service crops

Measuring carbon sequestration and soil fertility in Swedish forest gardens : a methodological study

Agroforestry is an old agricultural practice which has got renewed interest during the last decades as an alternative to industrialized agriculture. Agroforestry is a practice with potential to promote several ecosystem services, e.g. carbon seques-tration and soil improvement. This study looks into how carbon sequestration and soil fertility can be measured in one of the most diverse agroforestry systems; forest gardens. Five forest gardens located in southern Sweden were included in the study; Tystinge (T), Rikkenstorp (R), Hånsta Östergärde (H.Ö.), Holma skogsträdgård (H.o.) and Klockaregården (K), representing different soils, climates and manage-ments. Standing biomass was estimated for herbs, trees and shrubs. Herbal vegeta-tion was harvested and brought back to the lab, while trees and shrubs were meas-ured in the field and biomass was calculated by using allometric equations. Soil samples were collected to estimate root biomass, respiration, carbon content and C/N ratio. A soil profile description was performed, and a method to estimate my-chorrizal colonization was also tried out. It was shown that the biomass production and carbon in standing biomass varies depending on site and management. Previ-ous land use will determine whether the establishment of a forest garden will im-prove or impair biomass production. Herbal biomass was twice as high at T com-pared to H.Ö. Biomass of trees and shrubs varied as well, with the highest woody biomass being more than twice as high as the lowest, found at H.o. and K respec-tively. After the forest gardens had been established root biomass decreased with 60% at R, while it increased with 50% at H.Ö. At all sites soil respiration was lower in the forest garden than at reference spots outside the garden. The forest gardens seemed to favor earthworm activity, while no changes in carbon content or C/N ratio were seen. C/N ratios were strongly connected to the respective sites. For prop-er estimations of above- and belowground biomass of trees and shrubs more spe-cific allometric equations needs to be developed, suiting the species of relevance and the climatic conditions. A similar method would also provide the best estima-tion of herbal biomass. Carbon content in soils changes slowly and to see whether the forest gardens have had a long-term impact on carbon content new measure-ments needs to be made in the future. Respiration should be measured several times a year for reliable modeling of carbon sequestration to be possible. Data on degradation rates of different plant components are also needed for proper models on carbon flows to be developed. Better understanding of the components of forest gardens, and their interactions, would help in finding the potentials of forest gar-dens in Sweden

Assessing the effect of intercropped leguminous service crops on main crops and soil processes using APSIM NG

CONTEXT: To improve agricultural sustainability, alternative cultivation methods and assessment tools need to be developed. Integrating service crops (SC) can potentially increase cropping system multifunctionality and mitigate negative climate and environmental impacts of agriculture. OBJECTIVES: (1) Calibrate oats, winter wheat and red clover SC, grown as sole crops and intercrops, in the cropping system model APSIM NG for northern Europe climate conditions. (2) Use the calibrated crop modules to assess ecosystem processes from an intercropping system. (3) Discuss the role of mechanistic crop models in assessing ecosystem services and disservices from complex cropping systems. METHODS: The crops were calibrated with data from an oats-winter wheat cropping sequence at two field sites. Thirty weather datasets were created from historical weather data to generate weather-dependent variability in crop performance and related processes. The assessment compared two scenarios, with or without an intercropped red clover SC sown in oats and terminated the following spring in winter wheat. Outputs representing processes related to important ecosystem services were extracted from the simulations. RESULTS AND CONCLUSIONS: Calibration of the three crops resulted in satisfactory biomass levels at the end of the growing season. Including a SC reduced oat yield, but increased winter wheat yield in two-thirds of simulations. Model outputs showed that including a SC resulted in 33–79% more fresh soil organic carbon, depending on site, compared with no SC. Nitrogen (N) uptake by both crops was highest in the SC scenario. In oats, N losses did not differ between the two scenarios, while in winter wheat the SC scenario had approximately 50% lower N leaching losses and 30% higher gaseous N emissions. However, in the fallow period from winter wheat harvest through to spring, both types of N losses were elevated in the SC scenario. The SC scenario had only a minor effect on water dynamics, causing a small reduction in soil water content. SIGNIFICANCE: In this paper we give an example of how APSIM NG can be used to assess ecosystem services from complex agricultural systems using a case study with intercropping of cereals and leguminous SCs. APSIM NG was useful in providing a holistic assessment, and we show that intercropping with a SC can improve cropping system performance and reduce negative impacts, but long-term strategic management of N is required to prevent increased losses. To further improve simulation of intercrops more accurate simulation of early growth is needed for all crops included.</p

Temporal and Spatial Positioning of Service Crops in Cereals Affects Yield and Weed Control

Leguminous service crops (SCs) can provide multiple services to cropping systems, reducing the reliance on external resources if sufficient biomass is produced. However, rapid light and temperature reductions limit post-harvest cultivation of SCs in Northern Europe. A novel practice of intercropping SCs in two consecutive crops (spring-winter cereal) to extend the period of SCs growth, and hence improve yield and reduce weeds, was tested. Three spatial and temporal arrangements of SCs and cash crops were investigated, as well as three SC mixtures, characterized by their longevity and frost sensitivity. Compared to no SC, the best performing mixture, frost-tolerant annuals, increased grain and N yield of winter wheat by 10% and 19%, respectively, and reduced weed biomass by 15% and 26% in oats and winter wheat, respectively. These effects were attributed to high biomass production and winter survival. However, this SC reduced oat yields by 15% compared to no SC. Furthermore, SC growth and service provision varied largely between experiments, driven by the weather conditions. Extending the SC's growth period by intercropping in two consecutive cereal crops has potential, but locally adapted species choices and establishment strategies are needed to ensure SC vitality until termination

Data from: Management-induced micro-ecosystems in crop fields alter the functional trait composition of arable plant communities

&lt;p&gt;Data used for RLQ analysis. Include trait table, environment table and species table.&nbsp;&lt;/p&gt;&lt;p&gt;Traits/species table:&nbsp;&lt;br&gt;EQUAR, PLAMA and SPRAR were removed due to few observations. CHEPR and TAROF were removed due to lack of traits data.&lt;/p&gt;&lt;p&gt;Environmental table:&lt;br&gt;MD (mechanical disturbance) is a combination or location and a row-hoeing coefficient that assumes the impact of the hoe decrease with increasing distance from the centre of the hoe tine. cr hoed twice and ic hoed once both got a value of 2 and to distinguish them the latter was changed manually to 2.5&lt;/p&gt