Relative Yield Index Research Articles

Decomposition of production growth and identification of efficient cropping zones for major pulse crops in Uttar Pradesh and Uttarakhand

The study’s goal is to decompose pulse production growth in Uttar Pradesh and Uttarakhand and identify efficient copping zones for both states. The total change in production was decomposed into three effects, i.e., the area effect (ΔA. Y0), the yield effect (ΔY. A0.), and the interaction effect (ΔA. ΔY). The relative spread index (RSI) and relative yield index (RYI) were computed to identify the potential cropping districts for different pulses grown in Uttar Pradesh and Uttarakhand. We classified districts into four zones: most efficient, efficient, not efficient, and highly inefficient. A higher RYI corresponds to higher yield districts, and a higher RSI indicates a more cultivated area. Districts with a high relative spread index and a low relative yield index indicate that a particular pulse is not suitable for that district. We suggest addressing production issues through research, marketing, and extension services to enhance the productivity level of pulse crops. The results from Uttar Pradesh are highly encouraging, indicating that the yield effect has primarily contributed to the growth in pulse production. The government’s policies, schemes, and initiatives to promote pulse production and decrease imports are moving in the right direction. According to the methodological analysis, 57 districts are among the most efficient cropping zones for all selected pulse crops in Uttar Pradesh. In the case of Uttarakhand, for all selected pulses, 20 percent of districts come under the most efficient cropping zone, and 20 percent of districts come under the most efficient cropping zone. The highest 40 percent of districts fell under highly inefficient cropping zones. Lack of high-quality inputs, technology adoption, and poor market and extension services may be the reasons for low productivity in these districts. An increase in productivity with low costs could help the country reduce imports of pulses and check the flow of foreign currency.

Identification of potential districts for technology transfer in sesame (Sesamum indicum L.)

India is the largest producer of sesame in the world with an area of 16.22 lakh ha and production of 6.57 lakh t and contributing to 10.5% and 11.1% ofthe Worlds' area and production, respectively. The AICRP-sesame centreshave developed location-specific improved technologies, which can enhance sesame productivity significantly, but the awareness and adoption of these technologies among farmers is very low. Hence, focused efforts are requiredto transfer the existing technologies from the AICRP system to the farmers' fields through effective and efficient technology transfer programmes. To have focussed efforts for productivity enhancement and area expansion ofsesame, state-wise most efficient sesame cropping districts were identified by estimating the Relative Spread Index (RSI) and Relative Yield Index (RYI). Frontline demonstrations conducted in selected districts in the most efficient,efficient, and moderately efficient districts indicated a huge yield gap and vast potential to improve the sesame productivity under real farm situations. The extension strategies to be followed in technology transfer in variouscategories of districts for enhancing the productivity and area expansion of sesame crop are mentioned.

Methodology for assessing the agroecological adaptability of genotypes under global climate warming

Background. The relevance of the research is due to the fact that, despite the breeding achievements in releasing cultivars with high potential yield and resistance to the most common stressors in the regions, it is almost impossible to foresee and accurately predict the reaction of cultivars under production conditions. Besides, extreme weather events, including heat waves, droughts and downpours, will increasingly manifest themselves under global climate warming. To reduce the risk of a significant decrease in gross grain harvests in dry years and achieve high results under favorable conditions, the goal was to develop a comprehensive indicator for assessing the agroecological adaptability of genotypes to some consequences of global climate warming.Materials and methods. The results of a competitive test of 5 cultivars and 9 promising lines of spring wheat for their yield across six years contrasting in moisture availability by calculating the indicators of responsiveness to favorable conditions, grain yield depression under unfavorable conditions and the relative yield index were used to develop a complex indicator proposed to assess the agroecological adaptability of a genotype to contrasting environmental conditions.Results. The proposed method makes it possible to perform a comprehensive assessment that takes into account the responsiveness of an accession to improved agroclimatic conditions and the degree of its reaction to adverse environmental factors, taking into account the yield index in the studied set. The method is recommended for evaluating the source material and identifying the diversity of its responses to changes in agroclimatic conditions as well as for the stage of competitive variety testing in plant breeding for adaptability.

Effective management of Japanese black pine (Pinus thunbergii Parlat.) coastal forests considering tsunami mitigation

Coastal forests have been recognized to considerably reduce the energy of tsunamis and act as a measure against them. However, broken trees due to tsunamis produce woody debris and cause secondary damage to people and buildings. Thus, coastal forests have both positive and negative effects on tsunamis and people. To elucidate the relationships between these effects and forest management, three experimental forest management types were considered in this study: the sparse type (ST: 0.6 ? Ry ≦ 0.7), middle type (MT: 0.8 ? Ry ≦ 0.9), and dense type (DT: unthinned), where Ry is the relative yield index. In addition, numerical simulations were performed for the forest types considered. The effect of fluid force reduction depended on the growth stage of the forest stands and the occurrence of forest damage caused by the tsunami. For a tsunami height of 5 m, DT and ST exhibited the highest and lowest effectiveness in reducing the fluid force, respectively. However, when the tsunami height exceeded 15 m, the three management types exhibited almost the same effectiveness in reducing the fluid force. Moreover, tree damage increased with an increase in the tsunami height. All trees were damaged under all management types for a tsunami height greater than or equal to 15 m. Modes of tree damage included tree overturning and trunk breakage. The modes of tree damage for MT and ST were overturning only, and DT exhibited a combination of overturning and trunk breakage. Therefore, ST and MT are more suitable than DT for preventing trunk breakage. Thus, forest management against tsunamis should take estimated tsunami height into account for each region.

Identification of Efficient Cropping Zone for Major Vegetable Crops in Different Districts of Chhattisgarh

A study was carried out in the Department of Vegetable Science, IGKV Raipur to identify the efficient cropping zones for major vegetable crops grown in different districts of Chhattisgarh. Production and productivity of the Major Vegetable crops (Tomato, Potato, Chilli, Brinjal, Onion, Cauliflower, Cabbage and Okra) for 6 years (2004-05 to 2010-11) and 8 years (2011-12 to 2018-19) were collected from the Directorate of Horticulture and Farm Forestry (Department of Agriculture, Government of Chhattisgarh) and Directorate of Economics and Statistics, Government of Chhattisgarh. Two indices i.e. Relative Spread Index (RSI) and Relative Yield Index (RYI) were computed and the potential cropping districts for the study crops were identified. The outcome of study conducted from 2004-05 to 2010-11, revealed that out of 18 districts, three, one, four, three, four, two, four and two districts were found most efficient cropping zones (MECZ) for Tomato, Potato, Chilli, Brinjal, Onion, Cauliflower, Cabbage and Okra, respectively. Out of 18 districts, four, six, four, five, five, three, seven and six districts were fall under efficient cropping zones (ECZ) for Tomato, Potato, Chilli, Brinjal, Onion, Cauliflower, Cabbage and Okra, respectively. In Chhattisgarh, among 18 districts, six, five, four, three, three, four, two and five districts were considered as a less efficient cropping zones (LECZ) for Tomato, Potato, Chilli, Brinjal, Onion, Cauliflower, Cabbage and Okra, respectively. Similarly, out of 18 districts of the state, five, six, six, seven, six, nine, five and five districts were categorized under not efficient cropping zones (NECZ) for Tomato, Potato, Chilli, Brinjal, Onion, Cauliflower, Cabbage and Okra, respectively.
 Results obtained during 2011-12 to 2018-19 revealed that out of 27 districts, four, three, three, one, six, four, six and two districts were considered as most efficient cropping zones (MECZ) for Tomato, Potato, Chilli, Brinjal, Onion, Cauliflower, Cabbage and Okra, respectively. Similarly, seven, ten, eight, seven, five, five, five and six were under efficient cropping zones (ECZ) for Tomato, Potato, Chilli, Brinjal, Onion, Cauliflower, Cabbage and Okra, respectively. While, five, seven, six, six, six, six, five and eight districts were considered as a less efficient cropping zones (LECZ) for Tomato, Potato, Chilli, Brinjal, Onion, Cauliflower, Cabbage and Okra, respectively. Among 27 districts of the state, eleven, seven, ten, thirteen, ten, eleven, eleven and eleven districts are considered under not efficient cropping zones (NECZ) for Tomato, Potato, Chilli, Brinjal, Onion, Cauliflower, Cabbage and Okra, respectively.
 The outcome of analysis of long term data of area and production of vegetable crops grown in different districts of Chhattisgarh indicated that the area and production of various vegetable crops have been shifted from old districts two new districts during the period of 2004-2010 and 2011-2018.

Strategies for increasing area and productivity of sunflower (Helianthus annuus L.) in India

Sunflower (Helianthus annuus L.) is an important oilseed crop of India. There has been consistent decline in its production for last one and a half decade. The production has declined from 1.46 million tonnes (m t) in 2007–08 to 0.23 m t in 2020–21. A mission mode approach is required to increase the area and productivity of sunflower in the country. Relative Spread Index (RSI) and Relative Yield Index (RYI) were estimated for 181 districts to identify the potential areas. Based on RSI and RYI values of 250 and 125, these districts were grouped into four categories viz., most efficient, efficient, moderately efficient and inefficient. The inefficient districts were ignored. Of these, 11 and 13 districts were selected for productivity enhancement and area expansion, respectively. For these selected 24 districts, district-wise technologies were mapped. Front line demonstrations (FLDs) were conducted in six districts. In all the districts, FLDs plots recorded higher seed yield and gross monetary returns compared to farmers’ practice plots. Further, the strategies for productivity enhancement and area expansion were discussed.

Delineation of Efficient Paddy Cropping Zones in Andhra Pradesh

The research delineated efficient paddy crop zones in Andhra Pradesh. The area, yield and production of paddy were gathered from the Andhra Pradesh Department of Economics and Statistics to compute the Relative Spread Index (RSI) and Relative Yield Index (RYI). The definition of an efficient cultivation zone for paddy shows that in all nine districts of Andhra Pradesh there are numerous possibilities to increase overall paddy production. The primary source of irrigation is groundwater, comprising tubes and wells that cover 49 percent of net irrigation. The grade is of four types: Most Efficient Cropping Zone (MECZ) and Area Efficient Cropping Zone (AECZ) and Yield Efficient Cropping Zone(YECZ) and Not Efficient Cropping Zone (NECZ). It was noted that the West Godavari, East Godavari, Krishna, Guntur and Nellore are five districts inside Paddy's Most efficient cropping zone. Srikakulam and Vizianagaram are two districts within the Area efficient cropping zone. The Kurnool and Prakasam are two districts in which Yields efficient cropping zone. Visakhapatnam, Chittoor, Kadapa and Anantapur are four districts belong to the Not-efficient cropping zone. It is concluded that there was a lot of possibilities of increasing the overall production of paddy in all nine districts of Andhra Pradesh by delineating the efficient cropping zone for paddy. In the case of AECZ there is a need for popularisation of high-yielding cultivars, for better management technologies like the Rice Intensification System (RIS) and for integrated nutrient handling to increase yield levels and convert this zone into MECZ. In the case of YECZ, these sites offer promise for rice growing, although a decrease in water availability may be attributed to the less extensive area.

Delineating Efficient Cropping Zones of Potato and Chilli in Tamilnadu

Potato and Chilli are the most significant horticultural vegetable crops commercially cultivated in both field level and homestead gardening. India is leading producer of chilli and 2nd leading of potato in the world, but inadequate storage and huge unpredictable weather conditions leads to loses. This study was done to analyse trend changes in area, production and productivity over 30 years study period (1985-2015) and also identify Efficient Cropping zones of potato and chillies, at district level for Tamil Nadu during 2000-2015, in order to venture the hotspots of 21st century. Results of trend analysis revealed that potato production was decreasing till early 21st century and thereafter increasing gradually with respect to cropping area and chilli showed reduction in production over the years. Relative Yield Index (RYI) and Relative Spread Index (RSI) were used to figured out potential cropping districts for both crops over Tamil Nadu. Dindigul, Erode and Krishnagiri districts were found to be efficient cropping zone, while Nilgiris is sole district of Most Efficient Cropping Zone (MECZ) for potato. Virudhunagar district has been the Most Efficient Cropping Zone for chilli crop, while Ramanathapuram, Sivagangai, Tirunelveli, and Thoothukkudi districts were identified as potential efficient zone (ECZs) in Tamil Nadu. Hence, this paper attempts to identify the hotspot area and to study the deviation in cultivable land, production and productivity of the crops where farmers are facing most of the problems. The climate change scenarios could influence crop cultivation, and this paper is evident on the changes in efficient cropping zones.

Screening of forty Indian Amaranthus hypochondriacus cultivars for tolerance and susceptibility to tropospheric ozone stress

Tropospheric ozone stress adversely affects crop cultivars growth and productivity variably. The variable response of crop cultivars raised the need for identification of ozone (O3) stress-tolerant cultivars as an adaptive option. In the present study, forty cultivars of Amaranthus hypochondriacus were screened for susceptibility and tolerance to ozone stress. The cultivars were exposed to ambient (AO3) and elevated (EO3) ozone levels in free air ozone enrichment (FAOE) facility and monitored for foliar ozone injury symptoms appearance and yield attributes response. Foliar ozone injury symptoms on Amaranthus cultivars were interveinal yellow or black spots. Foliar ozone injury was observed in almost half of the cultivars and the maximum foliar injury (> 75%) was observed in cultivar IC-5527. The maximum yield reduction (> 90%) was observed in cultivars IC-4200 (94.9%) and IC-5569 (91.4%) compared to other cultivars. The results showed that Amaranthus cultivars exhibited variable response towards ozone stress where foliar ozone injury does not always correspond with grain yield reductions. Among the indices, Relative Yield Index (RYI), Stress tolerance (TOL), Abiotic Tolerance Index (ATI), Susceptibility Index (S) and Stress Susceptibility Index (SSSI) were positively correlated with relative yield loss in all the cultivars under ozone stress. With the help of cluster analysis and principal component analysis (PCA), the cultivars were categorized into ozone tolerant, moderately ozone tolerant and ozone susceptible category. The most tolerant cultivars were IC-5527 and IC-1733 which exhibited lower yield losses whereas the most susceptible cultivars were IC-3599 and IC-7924 having high foliar injury and maximum yield losses as compared to other cultivars. The most ozone tolerant cultivars of Amaranthus identified in this study may be recommended for cultivation to farmers in the areas experiencing EO3 during the Amaranthus crop growth period.

Effects of Different Application Rates of Organic Compound Fertilizer on Young Squash Growth and Soil Chemical Properties under Plastic Film House

To determine the replacement ratio of organic compound (OC) for basal application of inorganic fertilizers, the effects of different rate of OC on young squash (Cucurbita moschata) plant growth and soil chemical properties of plastic film house were investigated. The OC were applied at 50% (OC50+N50), 100% (OC100), and 150% (OC150) as the basal amount of inorganic nitrogen fertilizer recommended by soil fertility test, and the treatment were compared with inorganic NPK and PK treatment. The yield of young squash in OC150 treatment was similar to NPK treatment and higher than PK. In OC50+N50, OC100, and OC150 treatments, nitrate concentration and electrical conductivity (EC) were similar to NPK treatment. Relative nitrogen use efficiency of young squash ranged 17~37%. These results suggest that OC application as the basal dressing at the 150% level could be best rate to minimize nutrient accumulation of soil and to ensure the yield of young squash. Further study is required to evaluate effect of long-term application of OC on soil sustainability and young squash productivity. Changes of young squash yield according to replacement ratio of basal amount of nitrogen fertilizer with organic compound (OC) fertilizer. N, P, K, and OC mean nitrogen, phosphate, potash fertilizer, and organic compound, respectively. Treatment Fresh fruit weight Relative yield index† kg/10a % PK 8,607b† 96.0 NPK 8,960ab 100.0 OC50+N50 8,980ab 100.2 OC100 9,013ab 100.7 OC150 9,350a 104.5 †DMRT (p < 0.05). †Relative yield of other treatments to NPK treatment.

Influence of planting density and thinning on timber productivity and resistance to wind damage in Japanese larch (Larix kaempferi) forests

In recent years, forest damage caused by typhoons has occurred frequently in Hokkaido, northern Japan. According to predictive reports, a typhoon's intensity increases and it then maintains its intensity as it moves north. The relationship between this prediction and forest damage is not clear, but the importance of dealing with forest damage is increasing. Therefore, to consider the countermeasures in forest management, we evaluated the influence of planting density and thinning on timber yield and resistance to wind damage in Japanese larch (Larix kaempferi), which is one of the main tree species used for afforestation in northern Japan. In this study, the following three management types were investigated: sparse (ST: relative yield index < 0.8), middle (MT: relative yield index < 0.9), and dense (DT: unthinned). To assess resistance to wind damage, the critical wind speed required to overturn and break the trunks of trees was calculated using a mechanistic model. Furthermore, timber volumes were estimated from a stand age of 10–50 years using the Yield Prediction System. The management type and planting density (1500–2500 trees ha−1) affected resistance to wind damage. Scenarios with ST and low planting density (1500 trees ha−1) showed a high resistance. In contrast, total timber volumes for scenarios varied from approximately 440 to 630 m3 depending on the site index (SI = 22, 25, and 28) at a stand age of 50 years. The merchantable log volume of the final cutting varied from approximately 210 to 470 m3 depending on the management type, planting density, and SI. There was a negative linear correlation between the log volume and resistance to wind damage. Therefore, it is important to balance both the decreased wind damage risk and higher timber yield or to prioritize them.

Identification of efficient cropping zone for Redgram in Tamil Nadu

The methodological study was made in Department of Agronomy, Tamil Nadu Agricultural University (TNAU),Coimbatore. The study was conducted to identify the efficient cropping zone of redgram for Tamil Nadu. The data on area, production and productivity of Redgram for 1997-98 to 2011-12 were collected and indices such as Relative Spread Index (RSI) and Relative Yield Index (RYI) were computed and the potential cropping districts for the Redgram were identified. The results indicated that among the different districts in Tamil Nadu, Selam, Theni, Namakkal, Madurai, Vellore, Thiruvannamalai, Dharmapuri were most efficient cropping zone. Among all the districts of Tamil Nadu, Vellore had a high relative spreading index and while Theni had a high relative yield index. In some of the districts though RSI is low, RYI is high which indicates the suitability of that Redgram. Market demand and value of the produce, suitablility of the crop made farmers to cultivate redgram in their location which relates in low RSI with high RYI.

Identification of efficient cropping zone for major pulse crops in Tamil Nadu

An analytical study was carried over to identify the efficient cropping zone for cultivation of major pulses like Bengalgram, Pigeon pea, Greengram, Blackgram and Horsegram in Tamil Nadu. The data on area, production and productivity of the crops for the period from 1985-86 to 2015-16 (excluding 2014-15) were collected and analysed for their Relative Yield Index (RYI), Relative Spread Index (RSI).Based on the pooled result of the indices for thirty years the efficient cropping zones for the crops were identified. Cuddalore district for Blackgram, Salem, Virudhunagar and Tirunelveli districts for Greengram, Salem, Dharmapuri and Theni districts for Redgram, Coimbatore district for Bengalgram, Salem, Dharmapuri and Dindigul districts for Horsegram were identified as the most efficient cropping zones for the respective pulse crops.

Comparison of Different Land Evaluation Techniques for Evaluating the Soil Suitability for Rainfed Hybrid Cotton

This study compares the performance of three land evaluation methods, viz., FAO Simple Limitation, Storie Index and InfoCrop simulation model, for assessing the suitability of cotton soils (represented by nine different soil series) of Nagpur district, Maharashtra, India. The Simple Limitation method categorised Wardha, Parseoni and Bhugaon soil series as moderately suitable and the remaining are marginally suitable for rainfed cotton. The values of Land Index, determined by the Storie method, ranged from 20.3 for Manori series to 55.3 for Bhugaon series. Rainfed cotton yields, simulated by InfoCrop model ranged from 761 kg ha-1 in Manori series to 2881 kg ha-1 in Katol series. The Relative Yield Index (RYI) ranged from 0.154 for Manori series to 0.585 for Katol series. Kinhala, Katol and Takali soil series, classified as marginally suitable by the Simple Limitation method, were upgraded as moderately suitable by Sys parametric method. The results of InfoCrop model justified this up-gradation with the high values of RYI that ranged from 0.574 to 0.585. Soils of Manori and Hatodi series are not suitable for cultivating rainfed cotton. Soil depth, hydraulic conductivity and plant available water in the soil were critical factors governing cotton yield and ranking of soils for their suitability.

Delineation of Efficient Cropping Zone for Sugarcane over the Southern Indian States

Sugarcane is an important cash crop, contributing to 4.6 per cent of total agricultural output. In a few regions, though sugarcane had widespread area, the productivity is very less. In a few other regions, the productivity is very high but acreage under sugarcane is low. This warrants delineation of effective cropping zones for sugarcane. District wise statistics on area, production and productivity of sugarcane for southern Indian states was collected to compute Relative Spread Index (RSI) and Relative Yield Index (RYI) to classify the zones into Most Efficient Cropping Zone (MECZ), Area-Efficient Cropping Zone (AECZ), Yield Efficient Cropping Zone (YECZ) and Inefficient Cropping Zone (IECZ). Analysis indicated that the maximum efficient cane growing zone is in Tamil Nadu, followed by Karnataka, Andhra Pradesh and Telangana. Sugarcane is not preferred in Kerala due to the prevailing climatic conditions. This analysis helps in the identification of options for improving the sugarcane area and production

Degraded soil increases the performance of a dominant grass, Andropogon gerardii (Big bluestem)

Dominant grasses can suppress subordinate species in grassland restorations. Examining factors that influence performance of a dominant grass when interacting with subordinate forbs may provide insights for maintaining plant community diversity. The objective of our study was to determine how soils of different restoration ages and functionally different forbs influence the performance (using biomass and tillering rate as proxies) of a dominant grass: Andropogon gerardii. Sites included a cultivated field and two restored prairies (4 or 16 years after restoration) at Konza Prairie (NE Kansas). We hypothesized A. gerardii performance would be greater in more degraded soils and when interacting with legumes. Soil structure, nutrient status, and microbial biomass were measured in soil that was used to conduct the plant interaction study. Andropogon gerardii performance was measured during an 18-week greenhouse experiment using the relative yield index calculated from net absolute tillering rate and final biomass measurements in three soil restoration age treatments combined with four interacting forb treatments. Restoration improved soil structure, reduced plant-available nutrients, and increased microbial biomass. Relative yield index values of A. gerardii were greater with non-legumes than legumes. Andropogon gerardii performed best in degraded soils, which may explain the difficulty in restoring tallgrass prairie diversity in long-term cultivated soil. Results from this study suggest practices that promote soil aggregation and fungal biomass, coupled with including a high abundance of legumes in seed mixes could reduce dominance of A. gerardii and likely increase plant diversity in tallgrass prairie restorations.

Interactions between transplants of Phragmites australis and Juncus acutus in Mediterranean coastal marshes: The modulating role of environmental gradients

Interactions between two coastal marsh plants (Phragmites australis and Juncus acutus) were investigated along three natural gradients of salinity, water table and soil texture, variously combined in a microtidal Mediterranean coastal marsh. Our aim was to clarify to what extent plant interactions explain the occurrence of stands of both species, since they are not solely due to their tolerance to environmental conditions. We used a replacement series design of field transplants. Mortality and relative yield index of aerial biomass were analyzed to assess the outcome of interactions using Generalized Linear Mixed Models. Results show that mortality was entirely driven by natural gradients. Specifically, higher salinity and soil clay contents increased mortality in both species, whereas high water table increased survival only in P. australis. Growth was controlled by plant interactions and by natural gradients. According to these results P. australis can suppress J. acutus in waterlogged and non-saline conditions. Where water table is deeper, J. acutus can suppress P. australis along a wide range of saline conditions. In the driest situations both species exhibited mutual interference and, in some cases, P. australis can again suppress J. acutus. Facilitation occurred along the salinity gradient in situations that correspond to low, medium or high stress for the beneficiary species, pointing that exceptions to the stress gradient hypothesis may occur in systems including multiple stress gradients. Our results suggest that competitive interactions and environmental gradients are not fully responsible for plant distribution in microtidal coastal marshes.

Identification of Efficient Cropping Zone for Rice, Maize and Groundnut in Tamil Nadu

A methodological study was made at the Agro Climate Research Centre, Tamil Nadu Agricultural University, and Coimbatore during 2012 to identify the potential districts for cultivation of rice, maize and groundnut in Tamil Nadu. The data on area, production and productivity of study crops for 2000–‘01 to 2009–‘10 were collected and indices such as Relative Spread Index (RSI) and Relative Yield Index (RYI) were computed and the potential cropping districts for the study crops were identified. In Tamil Nadu, nine districts were found to be prospective regions for rice, seven districts for maize and three districts for groundnut as in these areas both the RYI and the RSI were high. In some of the districts, RSI is more for a particular crop, while the RYI is low indicating non suitability of that crop. However, due to other factors such as market demand and value of the produce, farmers cultivate the crops that are not suitable for their location which relates in high RSI with low RYI. Keywords: Efficient Cropping Zone, Relative Spread Index, Relative Yield Index.

Relationship between relative yield index and relative spacing index : theoretical derivation of the relationship and its characteristics

Relationship between relative yield index and relative spacing index : theoretical derivation of the relationship and its characteristics

The role of forest stand density in controlling soil erosion: implications to sediment-related disasters in Japan

The role of forest stand density in controlling soil erosion was investigated in Ehime Prefecture, Japan. The main objective was to compare soil erosion under different forest conditions including forest type, species composition, and stand density as influenced by thinning operations. Relative yield index (Ry) was used as an indicator of stand density to reflect the degree of management operations in the watershed. Eleven treatments were established based on the above forest conditions. Soil loss was collected in each of the 11 treatments after each rainfall event for a period of 1 year. The paper presents summary data on soil loss as affected by forest conditions and rainfall patterns. Findings showed that an appropriate forest management operation, which can be insured by stand density control, is needed to reduce soil loss. The present study plays an important role in clarifying technical processes related to soil erosion, while it helps linking these elements to current Japanese forestry issues and bringing new inputs to reducing sediment-related disasters in Japan.