Plant Demand Adapted Fertilization in Organic and Precision …
145
2.3 Organics Influence on Soil Health
The earliest rigorous comparisons showed evidence that differences between organic
agriculture and conventional agriculture cannot be explained by summing up single
ecological measures of biological activity. In long term field trials of over two decades
in Switzerland [55], organic (ORG) treatments differed fundamentally from conventional ones. The metabolic quotient for CO 2 or qCO 2 were highest in mineral fertilized soil, whilst the organic systems, which had received organic manure, showed
lower values (indicates that the microorganisms of manured soils need less energy
for maintenance). Lori et al. [53] conducted a meta-analysis of 56 studies from
different climatic zones and experimental duration ranging from 3 to 100+ years
and concluded that organic farming enhances total microbial abundance and activity
in agricultural soils on a global scale. Organic systems had 32–84% greater microbial biomass carbon, microbial biomass nitrogen, total phospholipid fatty-acids, and
dehydrogenase, urease and protease activities than conventional systems. Exclusively, the metabolic quotient as an indicator for stresses on microbial communities
remained unaffected by the farming systems. Categorical subgroup analysis revealed
that crop rotation, the inclusion of legumes in the crop rotation and organic inputs
are important farming practices affecting soil microbial community size and activity.
In arid soils, organic biodynamic fertilization improved the soil physical properties, organic carbon and microbiological properties—actinomycetes population,
16S rRNA content, glomalin content and soil enzymes significantly [4]. The culture
independent analysis of eubacterial 16S rRNA gene diversity showed that organically cropped farms and orchards had more diverse bacterial community compared
to the conventional. Actinobacteria were higher by 10% in organic cropping. Soil
biological quality was thus improved through an alteration of the microbial community structure and function by organic amendments which selectively modify the
environment and make soil ecosystems more sustainable and can hence be classified
as ‘ecosystems engineers’ [4].
3 Precision Nutrient Management
Nitrogen fertilization is of crucial importance in obtaining optimum yield, but it is
never easy to determine the optimal dose due to complex soil-plant-climate interactions and variable management. The development and implementation of site-specific
nutrient recommendations have been made possible by combining the Global Positioning System (GPS) and geographic information systems (GIS). Various remote
sensors could be used for this purpose such as satellite imagery, ground-based optical
sensors, ground-based reflective sensors, aerial imagery, and leaf chlorophyll sensors
[36] combined with soil and tissue testing [83]. Over-fertilization as a precautionary
principle leads to additional unnecessary costs and environmental problems of water
145
2.3 Organics Influence on Soil Health
The earliest rigorous comparisons showed evidence that differences between organic
agriculture and conventional agriculture cannot be explained by summing up single
ecological measures of biological activity. In long term field trials of over two decades
in Switzerland [55], organic (ORG) treatments differed fundamentally from conventional ones. The metabolic quotient for CO 2 or qCO 2 were highest in mineral fertilized soil, whilst the organic systems, which had received organic manure, showed
lower values (indicates that the microorganisms of manured soils need less energy
for maintenance). Lori et al. [53] conducted a meta-analysis of 56 studies from
different climatic zones and experimental duration ranging from 3 to 100+ years
and concluded that organic farming enhances total microbial abundance and activity
in agricultural soils on a global scale. Organic systems had 32–84% greater microbial biomass carbon, microbial biomass nitrogen, total phospholipid fatty-acids, and
dehydrogenase, urease and protease activities than conventional systems. Exclusively, the metabolic quotient as an indicator for stresses on microbial communities
remained unaffected by the farming systems. Categorical subgroup analysis revealed
that crop rotation, the inclusion of legumes in the crop rotation and organic inputs
are important farming practices affecting soil microbial community size and activity.
In arid soils, organic biodynamic fertilization improved the soil physical properties, organic carbon and microbiological properties—actinomycetes population,
16S rRNA content, glomalin content and soil enzymes significantly [4]. The culture
independent analysis of eubacterial 16S rRNA gene diversity showed that organically cropped farms and orchards had more diverse bacterial community compared
to the conventional. Actinobacteria were higher by 10% in organic cropping. Soil
biological quality was thus improved through an alteration of the microbial community structure and function by organic amendments which selectively modify the
environment and make soil ecosystems more sustainable and can hence be classified
as ‘ecosystems engineers’ [4].
3 Precision Nutrient Management
Nitrogen fertilization is of crucial importance in obtaining optimum yield, but it is
never easy to determine the optimal dose due to complex soil-plant-climate interactions and variable management. The development and implementation of site-specific
nutrient recommendations have been made possible by combining the Global Positioning System (GPS) and geographic information systems (GIS). Various remote
sensors could be used for this purpose such as satellite imagery, ground-based optical
sensors, ground-based reflective sensors, aerial imagery, and leaf chlorophyll sensors
[36] combined with soil and tissue testing [83]. Over-fertilization as a precautionary
principle leads to additional unnecessary costs and environmental problems of water