Comparison of Causality of Temperature and Precipitation on Italian Ryegrass (Lolium Multiflorum Lam.) Yield between Cultivation Fields via Multi-Group Structural Equation Model Analysis in the Republic of Korea

Abstract

This study aimed to compare the causality of climatic factors affecting the yield of Italian ryegrass (IRG) between upland fields and paddy fields, by multi-group structure equation modeling. The raw data (n = 728) on forage contains both yield, field type, and the plantation address were collected from the Rural Development Administration, Republic of Korea. The climatic factors were: growing days, temperature and precipitation-in autumn and next spring seasons-from the climate big data of the weather information system of Korean Meteorology Administration. In the result, the composition of climatic factors was similar, but the causality by the paths was different between upland fields and paddy fields. In particular, yield in the paddy fields was sensitive to autumn precipitation because of short growing days in the rice-rotation system. In the paddy fields, the precipitation effect in both autumn and the next spring indirectly affected the yield through temperature. The autumn temperature effect on yield in the paddy fields was 2.82 times greater than in the upland fields, between the two field types, the spring temperature effect was somewhat similar after wintering; thus, IRG cultivation in paddy fields should be limited to the south. However, there is greater suitability for IRG in the upland fields in the autumn, where the benefits of higher temperatures accumulate to offset effectively the short growing days. This study will assist in checking areas suitable for IRG cultivation as a winter forage crop in the Republic of Korea. In the future, the structure established in this study will be expanded by adding variables related to soil physical properties from soil information system and cultivation management from survey sheets.

Sowing ratio, NS fertilisation and interactions of Lolium sp. and Festulolium grown in mixtures with Trifolium repens

“…During the study period, the highest yield increase was obtained after the application of N 50 for mixtures LB + TR and LM + TR (50 : 50) -3.00-3.43 t/ha, in relation to the plots fertilised with N 30 . The mean DM yield was higher in the 1 st year of the study, compared to the 2 nd year in all the fertilisation treatments and types of (Kim and Sung 2019). Meteorological data for 2016-2017 showed that both average annual and the growing season temperatures were favourable for the yield.…”

Impact of abnormal climate events on the production of Italian ryegrass as a season in Korea

“…Therefore, for the low yields in the southern inland region, it was concluded that other factors, such as soil physical properties and cultivation management for wintering, also contributed to the survival of IRG. According to Kim and Sung [ 18 ], IRG yield in paddy fields was lower than in upland fields due to the short growing period by the rice-IRG rotation system. Therefore, climate is the most important factor, but other factors in the severe cold below zero also affected the yield difference.…”

“…According to Ko et al [ 24 ], the southern Korean Peninsula was divided into five regions by temperature distribution: northern inland, central inland, southern inland, coastal, and mountainous regions. In this study, the central inland, southern inland and coastal regions were selected because the northern inland and mountainous regions were not suitable for IRG cultivation [ 18 ]. Suwon (latitude: 37° 25′ N, longitude: 126° 98′ E, n = 321), Jeonju (latitude: 35° 84′ N, longitude: 127° 12′ E, n = 107) and Jeju (latitude: 33° 51′ N, longitude: 126° 53′ E, n = 135) were selected as representative locations for the central inland, southern inland and southern coastal regions, respectively.…”

“…Climate information collected from the Korea Meteorological Administration (KMA) has been used for various purposes in the Korean agricultural field [ 15 , 16 ]. As part of a complex natural eco-system, the information on climate and soil factors was used to generate the structure of causality contains their direct and/or indirect pathways for forage crops, such as IRG [ 17 , 18 ], forage barley [ 19 ] and forage rye [ 20 ]. Climate data were also used to identify the trends in yields and climatic factors as a form of climate change research in Korea [ 21 – 23 ].…”

Assessment of causality between climate variables and production for whole crop maize using structural equation modeling

“…Furthermore, the indirect effects of precipitation, temperature and soil properties were notable in the paddy fields [ 17 ]. Additionally, when comparing climatic causality between paddy fields and upland fields, the production of Italian ryegrass in the paddy fields was sensitive to temperature due to the short growing period caused by the rice-winter crop rotation system [ 18 ]. Studies on the causal relationship between climate and crop production were also carried out for forage barley [ 19 ] and forage rye [ 20 ].…”