Soil Fertility Management and Pest Responses: A Comparison of Organic and Synthetic Fertilization

Abstract

The objective of this study was to assess the effect of fertilization (organic or synthetic) and cabbage, Brassica oleracea L., cultivars ('K-Y cross' and 'Summer Summit') on the chemistry of cabbage and on the responses of a cabbage specialist Pieris rapae crucivora Boisduval. Cabbages were grown from seeds in the greenhouse with either organic, synthetic, or no fertilizer treatments. Trials of ovipositional preference and larval feeding were conducted to evaluate the effect of foliage quality on insect responses. In addition, the foliar chemistry (water, nitrogen, total nonstructural carbohydrates, sinigrin, and anthocyanin) was measured during the insect bioassays. The results indicated that butterflies preferred to lay eggs on foliage of fertilized plants. The larvae grew faster on plants fertilized with synthetic fertilizer, but there was no evidence that contents of sinigrin delayed the developmental time of the larvae. However, plants that received organic fertilizer had higher biomass. In summary, the results of this study suggested that proper organic treatment can increase a plant's biomass production and may have a lower pest occurrence.

Agroecological Principles for the Conversion of Farming Systems

“…Pooling results across all three farms showed that variance in egg laying was approximately 18 times higher among plants in conventionally managed soil than among plants grown under an organic regimen. Similar studies conducted in China by Hsu et al (2009) indicated that Pieris rapae crucivora butterflies preferred to lay eggs on foliage of chemically fertilised cabbage plants and the larvae grew faster on plants fertilised with synthetic fertiliser. The results of this study suggested that proper organic treatment can increase a plant's biomass production and exhibit a lower pest occurrence.…”

Varying responses of insect herbivores to altered plant chemistry under organic and conventional treatments

“…Four of the five glucosinolates identified were present in substantially higher concentrations in organically fertilized plants in both years, and the same effect was shown by the fifth compound (neoglucobrassicin) in 2007. Hsu et al (2009) also found an increase in a single glucosinolate (sinigrin) in Brassica grown in pots with an organic soybean meal treatment compared with those in synthetic fertilizer. Brassica glucosinolate concentrations often decrease in response to increasing fertilizer or nitrogen supply (Fischer 1992;Chen et al 2004;Aires et al 2006;Schonhof et al 2007), but, with the exception of glucoiberin, we found no effect of fertilizer quantity on glucosinolate concentration.…”

Agroecology: Principles for the Conversion and Redesign of Farming Systems

“…Pooling results across all sampled farms showed that variation in egg laying was 18 times higher among plants grown in conventionally managed soil than among plants grown on organic soils [57]. In similar studies conducted in China by Hsu et al [58] indicated that Pieris rapae crucivora butterflies preferred to lay eggs on foliage of chemically fertilized cabbage plants and the larvae grew faster on plants fertilized with synthetic fertilizer. The results of this study suggested that a proper organic treatment can increase plant's biomass production and exhibit a lower pest occurrence.…”

“…Soils with high organic matter and rich biological activity exhibit complex food webs populated by beneficial microorganisms that prevent pathogen infection and insect pest incidence [58]. It may be argued that diversified agroecosystems whose nutrient cycling is mediated by the soil food web possess greater ecological stability, as well as resilience to external perturbation [50].…”