FG Bodenschutz und Rekultivierung
Agroforestry systems are receiving increasing attention in the temperate region due to their ability to counteract negative consequences of intensively managed agricultural fields. Examples of traditional agroforestry (AF) in central Europe are orchard meadows "Streuosbt", hedgerows "Knicks" and windbreaks. Traditional AF systems are considered to be areas of high natural and cultural value (HNCV), and as such have been recognized to support high biodiversity levels. Recently, modern AF systems which are well adapted to the current farming practices and are compatible with mechanized agriculture have emerged. Modern practices such as alley cropping system for woody biomass production (ACS), composed of strips of fast growing trees and agricultural crops grown in alleys between the tree rows, can supply market goods and environmental services at the same time (Gruenewald et al. 2007, Quinkenstein et al. 2009). However, farmers in Germany have been reluctant to implement the latter systems, because agricultural policies have limited the number of trees within agricultural systems, while the former have been in danger of abandonment throughout Europe. As a result many farmers have lost interest in AF, and those that inherited land with traditional AF systems may not recognize them as such, because they are not recognized as AF according to the EU policy. The aim of this work was to investigate familiarity with agroforestry in Germany.
Agroforestry for arable farmers is not a common practice in Germany. However, alley cropping for woody biomass production is of interest because of its high potential to concurrently provide a biomass feedstock and an arable crop. One of the systems that exists, although at an experimental level, is the integration of rows of fast growing trees, such as poplar or willow, with arable crops.
The experimental plots were initially established as part of the German joint research project “AgroForstEnergie - Economic and Ecological Evaluation of Agroforestry Systems in Farming Practice“, funded by the German Federal Ministry of Food and Agriculture (AgroForstEnergie 2015). The goal of this project was to study alley cropping systems, which concurrently produce a woody biomass feedstock and conventional agricultural crops. Currently the work is continued through the AGFORWARD Project.
The State of Brandenburg is known for its light sandy soils that are prone to wind erosion. The introduction of tree hedgerows within the agricultural landscape can reduce wind erosion (Böhm et al. 2014). In addition, microclimatic conditions such as soil moisture, wind speed reduction, relative humidity and air temperature have been more favourable for plant growth in crop alleys compared to reference crop areas (Böhm et al. 2014; Quinkenstein et al. 2009).
Sugar beets are a common crop for conventional agricultural systems in Western Europe. As part of agroforestry systems, sugar beets have rarely been studied. Even though sugar beets can root up to a depth of 2 meter, their yields can be significantly reduced due to a lack of water (Hoffmann 2010; Bloch et al. 2006). Agroforestry systems that consist of tree hedgerows and crop alleys, also known as Alley Cropping Systems, have the potential to increase plant moisture in comparison to conventional agricultural systems (Quinkenstein et al. 2009).
This study aims to assess tree hedgerow effects on sugar beets. The objectives of this study were to; 1) assess how tree hedgerows planted at three distances affected sugar beet yields; 2) to correlate soil moisture values of the top 15 cm with sugar beet yields at the same distance of the tree row; 3) to assess the effects of drought stress on sugar beet yield.
Agroforestry (the integration of trees with crop and/or livestock production) offers a pathway to diversify agricultural production. Agroforestry systems have the potential to improve on-farm use of water through enhanced soil water holding capacities, the provision of shade, and the creation of wind shelter. These three characteristics can also improve the resilience of agricultural production in response to changing weather patterns. The objectives of this study were: 1) to measure how alley cropping systems with varying alley widths affect crop microclimate, 2) to measure the effects of this microclimate on sugar beet (Beta vulgaris) yields, and 3) to assess how moisture availability affects sugar beet growth patterns. Measurements were made in a 70 ha alley cropping system comprising black locust (Robinia pseudoacacia L.) and hybrid poplar Max1 (Populus suaveolens subsp. maximowiczii x P. nigra). A sugar beet crop was grown during the relatively dry growing season of 2015. Sugar beet yields were reduced in close proximity to the hedgerow, but yields were higher at and beyond an intermediate distance when compared with those in a nearby conventional agricultural field. Moisture availability significantly affected growth patterns of sugar beet roots.
Inorganic phosphorus (P) plays an important role as plant nutrient in fertilizers, but also as a major pollutant to aquatic ecosystems by leaching from arable land. The mobility and bioavailability of P depends on adsorption, desorption and precipitation processes at soil mineral surfaces. In the soil matrix, P can be found in the forms of iron, aluminum or calcium complexes, adsorbed on mineral surfaces. P reactions in soil, especially the fixation on iron and aluminum (hydr) oxides, have been thoroughly studied. But the much slower process of P release has to be attended as well regarding the prospective supply of fertilizers and the use of plant available P pools in arable soils. The P adsorption ability of pedogenic oxides depends on their crystallinity, while soils contain both crystalline minerals such as goethite or ferrihydrite, as well as amorphous iron and aluminum compounds. In this study, long-term adsorption and desorption experiments were carried out to investigate the P binding mechanism during the sorption processes at certain time steps. For adsorption experiments, various experimental conditions such as pH, P ionic strength, competitive ions such as SO4 2- and Ca2+ as well as time will be considered. For desorption experiments, a Flow-Through-Reactor-Technique will be applied to investigate desorption kinetics and processes under nearly natural conditions without disturbance of the mineral-solution interface. Additionally, the release of P from the iron and calcium phosphates vivianite and hydroxyapatite, a main supplier of inorganic P and model substance for bone char, will be investigated. By using Fourier-Transformation-Infrared-Spectroscopy, changes of P binding mechanisms during ad- and desorption processes and easily as well heavily purgeable P can be detected. Aim is to identify fundamental processes of P fixation and mobilization as well as to specify similarities and differences of P binding on crystalline and amorphous reactive surfaces of pedogenic oxides.
The use of sewage sludge as fertiliser is a common practice in Europe, where sewage sludge is usually applied on a plant-available N or total metal concentration basis; as a result, phosphorus (P) concentrations can be well above crop needs. The objective of the study was to evaluate the effect of three doses of sewage sludge (0, 200, and 400 kg total N ha⁻¹ year⁻¹) combined with lime (2.5 Mg CaCO3 ha⁻¹) or without lime on the P in soil and pasture, tree growth and pasture production in a silvopastoral system established with Populus canadensis Moench over seven consecutive years. The P availability varied with the soil pH (a result of lime and sewage sludge applications) throughout the study. In general, an increase of the soil acidity (pH 5.39) increased the amounts of Fe and Al in the soil solution, which form very strong bonds with P, thereby reducing the P availability (M3-P: 20.99 g kg⁻¹). The effect of lime on the P availability gradually declined in the years following its application. However, in the latter part of the study (2007–2008), due to the higher residual effect of the sewage sludge compared with lime, the doses of sewage sludge (200 and 400 kg N total ha⁻¹) increased the concentrations of P (200N: 37.31 g kg⁻¹ and 400N: 48.71 g kg⁻¹) and Fe (200N: 321.51 mg kg⁻¹ and 400N: 341.56 mg kg ⁻¹) in a Mehlich 3 solution, the concentration of P in the pasture (200N: 2.53 g kg⁻¹ and 400N: 2.81 g kg⁻¹) and the amount of P extracted by the pasture (200N: 8.78 kg ha⁻¹ and 400N: 10.34 kg ha⁻¹), resulting in possible reduction in environmental problems. Further, due to its agronomic benefits as a source of plant nutrients and organic matter, fertilisation with high quality sewage sludge could be recommended for silvopastoral systems under edaphoclimatic conditions similar to those in this study.
Als mehrjährige Bioenergiepflanze kann Sida hermaphrodita eine wichtige Rolle für den Anbau auf marginalen Standorten in der nahen Zukunft spielen. In einem kontrollierten Topfexperiment wurde der Einfluss von verschiedenen Kompostgehalten (10, 20, 30, 50%) und mineralischem Stickstoffdünger (100 kg N ha–1) auf Biomasse, Wuchshöhe und Kohlenstoffallokation während der Etablierungsphase untersucht. Weiterhin wurden ökophysiologische Parameter (Gaswechsel, Chlorophyllfluoreszenz, Chlorophyllgehalte) mit nicht-destruktiven Methoden bestimmt. Die Ergebnisse des Experimentes zeigen, dass sowohl die Stickstoffdüngung als auch die Kompostgabe positive Effekte für das Wachstumsverhalten hat. Während der Etablierungsphase erreichten die gedüngten Pflanzen eine mittlere Pflanzenhöhe von bis zu 127 cm (maximale Wuchshöhe 168 cm). Die Photosynthese wurde nicht durch die unterschiedlichen Behandlungen beeinflusst. Die mittlere CO2-Austauschrate variiert zwischen 5,8 und 9,9 μmol m–2 s–1 und die Elektronentransportrate zwischen 34,5 und 53,9 μmol m–2 s–1. Die Verwendung von Kompost und Stickstoff ist für eine bessere Biomasseproduktion von Sida in marginalen Böden möglich, auch wenn das Wachstum im ersten Jahr limitiert ist und es negative Rückwirkungen auf die Bestandesetablierung gibt.