Comparative Assessment of Different Crop Rotation Schemes for Organic Common Bean Production

Abstract

The aim of the current study was to contribute to the establishment of sustainable organic crop rotation schemes for common bean under mild-winter climatic conditions. Common bean was cultivated according to organic or conventional farming practices during spring-summer in two successive years with crop and treatment during the preceding winter as either: (a) organic broccoli, (b) conventional broccoli, (c) organic faba bean used as green manure, or (d) fallow. Common bean was either inoculated with Rhizobium tropici CIAT 899 or non-inoculated, while faba bean was inoculated or non-inoculated with Rhizobium laguerreae VFLE1. Inoculating faba bean with rhizobia enhanced dry biomass production and biological N-fixing ability in both experimental years. Furthermore, organic farming did not restrict the yield of broccoli compared to conventional practices during the first year, while the reverse was the case in the second year, due to reduced soil N availability. Furthermore, green manure enhanced the fresh pod yield in the following organic crop of common bean in both years. The lowest yield was recorded in organically grown common bean when the preceding winter crop was organically grown broccoli in both years. Rhizobia inoculation of the common bean during the first year slightly increased atmospheric N fixation by common bean.

Impact of Legumes as a Pre-Crop on Nitrogen Nutrition and Yield in Organic Greenhouse Tomato

“…An additional reason is that the BNF efficiency of faba bean is not particularly affected by the level of inorganic N in the soil, presumably because this plant has a relatively low efficiency to exploit the soil N [ 25 , 26 , 28 ]. Furthermore, the N 2 fixation efficiency of common bean is generally lower than that of other legumes, according to several studies [ 21 , 23 , 26 ]. The present study confirmed the lower N 2 fixation efficiency of common bean as the %Ndfa in this legume was appreciably lower than that found in cowpea and faba bean.…”

“…Crop rotations are the cornerstone of organic farming systems, as they contribute crucially to both maintenance of soil fertility [ 21 ], and control of pests, diseases and weeds [ 22 ]. Therefore, many scientists have proposed the reintroduction of legumes into the crop rotation systems, as they act as N fertilization sources for the next crop.…”

Hydroponic Common-Bean Performance under Reduced N-Supply Level and Rhizobia Application

“…Similar reports concerning the relation between inorganic-N input and C:N ratio were also found in the study by Kontopoulou et al [ 56 ], in which the limited N-availability in an organic common-bean crop increased the shoot C:N ratio compared to that found in plants grown conventionally. In contrast, Karavidas et al [ 57 ] found that although the organic farming practices restricted the soil N availability, the N content and the C:N ratio in common bean shoots were not influenced. This discrepancy was presumably because the shortage of soil N in the study by Karavidas et al [ 57 ] was less restrictive than those of the current study, and those of Kontopoulou et al [ 56 ].…”

Legume-Based Mobile Green Manure Can Increase Soil Nitrogen Availability and Yield of Organic Greenhouse Tomatoes

“…While the classic method of legume-based green manuring in the field offers only N and also provides some benefits with respect to phosphorus (P) availability, MGM enriches the soil with all of the macronutrients and trace elements that are necessary for plant growth. On the other hand, part of the benefit of legume crop rotation is due to the improvement of the soil properties and the reduction of plant pathogens [10,11,26]. This benefit is lost when MGM is applied.…”