Life cycle assessment of organic paddy rotation systems using land- and product-based indicators: a case study in Japan

Abstract

Purpose This study aims to compare crop rotation systems used in organic farming (organic rotation systems) with those of both conventional farming (conventional rotation systems) and continuous rice cropping systems. Life cycle assessment (LCA) is performed based on land-and product-based indicators. Methods Seven crop rotation systems for rice, barley, and soybeans and continuous rice production systems were evaluated in this study. These systems are practiced by farmers in the study region and were constructed using production records, statistics, and guidelines. Comparisons were then made between organic and conventional crop rotation systems and between these crop rotation systems and a continuous rice production system. We used land-oriented expression to analyze tradeoffs between physical and monetary productivity and the environmental impact per area unit and productoriented expression to analyze efficiency as measured by the environmental impact per product unit. Results and discussion Results are summarized as follows: (1) The product-oriented expression, which is equivalent to conducting product LCA, revealed that organic conversion tended to be efficient, irrespective of using physical productivity (the functional unit of product mass measured as averaged annual energy yield) or using monetary productivity (the functional unit of product mass measured as averaged annual income).(2) However, the land-oriented expression revealed that there were tradeoffs between physical productivity and environmental impacts, although these tradeoffs were converted to win-win relationships if monetary productivity was used instead of physical productivity, and (3) the alteration of a continuous rice production system into crop rotations tended to be efficient and enables a win-win relationship.Conclusions Organic rotation systems have the potential of being recommended as sustainable agricultural practices in comparison with conventional rotation systems and continuous (organic and conventional) rice production systems. However, it was not clarified which productivity concepts should be used as evaluation criteria. It is considered that further studies using mechanistic modeling of crop rotations are required to improve LCA practices.

Optimization Model for Mitigating Global Warming at the Farm Scale: An Application to Japanese Rice Farms

“…Under net farm income maximization, both farms selected early-and medium-maturing rice varieties that generated larger crop incomes compared with very early-and late-maturing rice varieties, and reduced rice cultivation to 50% of the total farmland because the total crop income from a wheat-soybean rotation, which depended on a large subsidy, was greater than that from a rice cultivation (Table 3) [53]. In both farms, family labor resources were exhausted in early June, early July, and late July, and additional labor inputs from temporary workers were required to avoid labor shortages in early June and late July.…”

Implementing farm-level environmental sustainability in environmental performance indicators: A combined global-local approach

“…The environmental performance of a farm is quantified by relating the environmental impact of the farm to the FU in question. The choice of FU is highly dependent on the aim of the investigation (de Boer, 2003;Schau and Fet, 2008;Hokazono and Hayashi, 2015;van der Werf and Salou, 2015). Basically, three main groups of FUs can be distinguished: product-based, area-based, and financial FUs.…”

Addressing crop interactions within cropping systems in LCA

“…The cropping systems and crop assessment are also particularly complex with regard to nutrient dynamics which affect the yield and environmental performance. In particular, nutrient availability is not constant and can be affected by previous crops, crop management and soil characteristics (Goglio et al 2014;Hokazono and Hayashi 2015;Kulak et al 2013;Mazzoncini et al 2008;Nemecek et al 2015). For instance, N availability is affected by residue, manure and fertiliser application, soil cultivation and the system involved may occur within the same season or in the following seasons, thus affecting the performance of the following crops (Brady and Weil 2002;Peter et al 2017).…”

“…The effect of cropping systems on single crops has been widely discussed (Brankatschk and Finkbeiner 2015;Hokazono and Hayashi 2015;Peter et al 2017), including the benefits of cropping systems on agronomic and economic performance, soil fertility and environmental pollution (Brady and Weil 2002;Goglio et al 2012;Hokazono and Hayashi 2015). In cropping systems, it has been observed that the performance of a crop is often significantly affected by the previous crop in the cropping system (Hokazono and Hayashi 2015;Knudsen et al 2014;Nemecek et al 2015;Peter et al 2017). Several effects of crop management can have long term consequences on soil organic matter, nitrogen availability, weed population, biodiversity (Brady and Weil 2002;Goglio et al 2015;Knudsen et al 2017).…”