Jörn Germer

Skyfarming an ecological innovation to enhance global food security

Population growth increases the demand for food and thus leads to expansion of cultivated land and intensification of agricultural production. There is a definite limit to both of these options for food security and their multiple negative effects on the environment undermine the aim for sustainability. Presently the impact of the Green Revolution on crop production is levelling off at high yields attained and even the potential of large scale irrigation programmes and transgenic crops seem to be limited in view of the expected increase in demand for food. Moreover, climate change threatens to affect agricultural production across the globe. Skyfarming represents a promising approach for food production that is largely environment independent and therefore immune to climate change. Optimal growing conditions, shielded from weather extremes and pests are aimed at raising plant production towards the physiological potential. Selecting rice as a pioneer crop for Skyfarming will not only provide a staple for a large part of the global population, but also significantly reduce the greenhouse gas emission caused by paddy cultivation. Multiplication of the benefits could be achieved by stacking production floors vertically. In Skyfarming the crop, with its requirements for optimal growth, development and production, determines the system’s design. Accordingly, the initial development must focus on the growing environment, lighting, temperature, humidity regulation and plant protection strategies as well as on the overall energy supply. For each of these areas potentially suitable technologies are presented and discussed.ZusammenfassungDer steigende Bedarf an Nahrungsmitteln infolge einer weiterhin exponentiell wachsenden Weltbevölkerung erfordert enorme Anstrengungen seitens der Agrarwirtschaft, die bislang mit Ausdehnung der Anbauflächen und mit Intensivierung der landwirtschaftlichen Produktion reagierte. Beiden Optionen zur Sicherung der Welternährung sind physische und biologische Grenzen gesetzt und die landwirtschaftlichen Aktivitäten führen ihrerseits zu mannigfaltigen Umweltwirkungen, die die ökologische Tragfähigkeit der Erde mindern können. Durch die Grüne Revolution konnte ein rasanter Anstieg der Nahrungsmittelproduktion erreicht werden, jedoch ist in einigen Regionen das Ertragspotential bestimmter Feldfrüchte nahezu erreicht und die Erwirtschaftung zusätzlicher Ertragssteigerungen wird zunehmend schwieriger. Auch der mögliche Beitrag von Bewässerungsprogrammen und seitens genetisch veränderter Varietäten scheint angesichts des zu erwartenden Anstiegs beim Nahrungsmittelbedarf begrenzt. Darüber hinaus sind negative Auswirkungen des Klimawandels auf die landwirtschaftliche Produktion zu erwarten. Skyfarming ist ein Ansatz zur weitgehend umwelt- und somit klimaunabhängigen Nahrungsmittelproduktion im Hochhaus. Unter optimalen Wachstumsbedingungen, geschützt vor Wetterextremen und Schadorganismen soll das physiologische Produktionspotential der Pflanzen weitestgehend ausgeschöpft werden. Mit Reis als Modellpflanze für Skyfarming wird einerseits ein wichtiges Grundnahrungsmittel bereitgestellt und andererseits die Möglichkeit eröffnet die durch den Naßreisanbau verursachte Emissionen klimarelevanter Gase signifikant zu reduzieren. Eine Vervielfachung des Ertrages ließe sich durch die vertikale Anordnung mehrerer Produktionsebenen erreichen. Bei Skyfarming steht die Kulturpflanze, mit ihren spezifischen Ansprüchen für optimale Entwicklung und Wachstum im Vordergrund eines systemischen Ansatzes. Dementsprechend muss der Fokus zu Beginn der Technologieentwicklung auf folgende Bereiche gerichtet sein: Wachstumsraum, Beleuchtung, Temperatur, Luftfeuchteregulierung, Pflanzenschutzstrategien, sowie – übergeordnet – Energieversorgung. Für jeden dieser Bereiche werden entsprechende Technologien vorgestellt und diskutiert.

Temperature and deactivation of microbial faecal indicators during small scale co-composting of faecal matter

Small scale co-composting of faecal matter from dry toilet systems with shredded plant material and food waste was investigated in respect to heat development and deactivation of faecal indicators under tropical semiarid conditions. Open (uncovered) co-composting of faecal matter with shredded plant material alone did not generate temperatures high enough (<55 degrees C) to reduce the indicators sufficiently. The addition of food waste and confinement in chambers, built of concrete bricks and wooden boards, improved the composting process significantly. Under these conditions peak temperatures of up to 70 degrees C were achieved and temperatures above 55 degrees C were maintained over 2 weeks. This temperature and time is sufficient to comply with international composting regulations. The reduction of Escherichia coli, Enterococcus faecalis and Salmonella senftenberg in test containment systems placed in the core of the compost piles was very efficient, exceeding 5log10-units in all cases, but recolonisation from the cooler outer layers appeared to interfere with the sanitisation efficiency of the substrate itself. The addition of a stabilisation period by extending the composting process to over 4 months ensured that the load of E. coli was reduced to less than 10(3)cfu(-g) and salmonella were undetectable.

Effect of biochar, clay substrate and manure application on water availability and tree-seedling performance in a sandy soil

ABSTRACT In order to develop a method for extensive pomiculture on marginal soils in semiarid Brazil, a field experiment was conducted to study the impacts of the soil conditioners biochar, clay substrate and goat manure on soil physical parameters of a sandy soil and on seedling performance of Spondias tuberosa Arruda. Manure significantly increased total porosity, soil water content and reduced bulk density of the sandy soil. Water content at field capacity (θfc) and at permanent wilting point (θpwp) were increased due to manure application. Neither biochar nor clay substrate had a significant impact on the soil physical parameters. Biochar combined with clay substrate led to lower soil water content and significantly reduced the period of retaining atmospheric water. Due to a strong correlation (R2 = 0.75) between θfc and θpwp, the available water capacity within all treatments remained unchanged. Amelioration and initial nutrient supplies had no effect on seedling survival and stem growth of S. tuberosa during the 23-month experiment. This underlines the nondomesticated character of the available plant material of S. tuberosa. The independence of the seedling performance of soil management makes S. tuberosa an interesting species for low-input orchards and for reforestation within the Caatinga.