Characterization of Helicoverpa armigera spatial distribution in pigeonpea crop using geostatistical methods.

BACKGROUND: The gram pod borer, Helicoverpa armigera (Lepidoptera: Noctuidae) is an economically important pest of pigeonpea crop in India. Fixed plot surveys for H. armigera larvae were carried out at 28 pigeonpea fields located in the Southern Plateau and Hills agro-climatic zone of India for three crop seasons (nine sampling weeks per season). The spatiotemporal dynamics of H. armigera larvae in the experimental area (=Hanamkonda) was analysed using geostatistics tools, namely a variogram and Voronoi diagram, and H. armigera larval distribution patterns were further characterized and mapped. RESULTS: A significant difference in H. armigera larval incidence was noticed between sampling weeks, with greater larval incidence observed between 26 November and 2 December. Pod formation phenophase (Meteorological Standard Week 44) of pigeonpea favoured the initial H. armigera larval incidence. Variogram analysis revealed moderate to strong larval aggregation (spatial dependence) of H. armigera in all nine sampling weeks. Based on the range value of the variogram, the average aggregation distance of H. armigera larvae in pigeonpea was estimated to be 2425.48 m. Voronoi diagrams illustrated the spatial heterogeneity of H. armigera larva between sampling weeks, which can be linked to availability of food sources. CONCLUSION: This study witnessed intrapopulation variability in H. armigera larvae associated with geographical space and temporal patterns. Based on our findings, a sampling distance of 2425.48 m may be used in larger pigeonpea fields (experimental area) to reduce scouting fatigue. The interpolated maps generated in this study may be of value in developing effective H. armigera larva monitoring and management tools in pigeonpea crop.

Impact of 28 year old agroforestry systems on soil carbon dynamics in Eastern Himalayas.

Globally, various estimates are available on the above-ground (plant parts) carbon (C) sequestering potential of agroforestry systems (AFSs). However, information on soil organic carbon (SOC) sequestration potential is limited for AFSs. Furthermore, the impacts of AFSs established for the restoration of C in degraded soils (prone to soil erosion, C and nutrients loss, etc.) of Himalayas are rarely investigated. Thus, a study was conducted on an agroforestry block established in 1989 at the Indian Council of Agricultural Research (ICAR), Research Complex for North Eastern Hill (NEH) Region, Lembucherra, Tripura, India. The AFSs comprised of four multipurpose tree species viz., teak (Tectona grandis Linn), sissoo (Dalbergia sissoo Roxb. Ex DC.), eucalyptus (Eucalyptus globulus L.), and neem (Azadirachta indica A. Juss) in combination with pineapple (Ananas comosus L. merr.). Planted in three times replicated randomized block design. After 28 years of establishment, the impacts of these AFSs were assessed on SOC stocks and its fraction pools. Results revealed that sissoo + pineapple system stored the highest SOC stocks in 0-15 cm (22.1 ± 1.4 Mg/ha) and 30-60 cm (18.0 ± 4.3 Mg/ha) depths, whereas the SOC stocks in 15-30 cm (12.2 ± 1.2 Mg/ha) and 0-30 cm (34.0 ± 1.6 Mg/ha) were the highest under teak + pineapple. When considering the entire 0-100 cm soil profile, the SOC stocks ranged between 65.3 and 71.6 Mg/ha across the diverse AFSs which was significantly higher than that under cultivated land (52.8 ± 2.6 Mg/ha). The sissoo + pineapple system had the highest SOC stock in 0-100 cm (71.6 ± 5.8 Mg/ha). The share of passive carbon (PC, less labile + non-labile) pools to SOC stocks under AFSs followed the order of sissoo + pineapple > teak + pineapple > neem + pineapple > eucalyptus + pineapple. The PC or recalcitrant pools of SOC stocks at 0-100 cm were 54.2-60.6% under various AFSs. Results revealed that the establishment of AFSs with pineapple on degraded lands increased a significant amount of C and had a considerable effect on soil quality in comparison to C present in soils under cropland. Thus, a large scale adoption of AFSs may restore C lost through the cultivation of the crop in degraded lands and provide a feasible option for livelihood through concurrent cultivation of multipurpose tree species and agri-horticulture crops.

Impact of land configuration and organic nutrient management on productivity, quality and soil properties under baby corn in Eastern Himalayas.

Appropriate land configuration and assured nutrient supply are prerequisites for quality organic baby corn (Zea mays L.) production in high rainfall areas of the delicate Eastern Himalayan Region of India. A long term (5-year) study was conducted during 2012-2016 on a sandy loam soil in the mid attitude of Sikkim, Eastern Himalayan Region of India to evaluate the productivity, produce quality, the profitability of baby corn, and soil properties under different land configurations comprising flatbed, ridge and furrow, and broad bed and furrow, and organic nutrient management practices comprising un-amended control, farmyard manure 12 t ha-1, vermicompost 4 t ha-1 and farmyard manure 6 t ha-1 + vermicompost 2 t ha-1. The baby corn sown on broad bed and furrow had the tallest plant (149.25 cm), maximum dry matter (64.33 g plant-1), highest leaf area index (3.5), maximum cob length (8.10 cm), cob girth (6.13 cm) and cob weight (8.14 g) leading to significantly higher fresh baby corn yield (1.89 t ha-1), and net returns (US$ 906.1 ha-1) than those of other treatments. Mineral composition (phosphorus, potassium, iron, and zinc), protein, and ascorbic acid content were also the highest in baby corn grown under the broad bed and furrow system. The soil of broad bed and furrow had a higher pH, organic carbon content, organic carbon pools, microbial biomass carbon, and enzymatic activities (dehydrogenase, fluorescein diacetate, and acid phosphatase) compared to soils of other land configurations. A combined application of farmyard manure (6 t ha-1) + vermicompost (2 t ha-1) improved the crop growth and produced 117.8% higher fresh baby corn and 99.7% higher fodder yield over control (0.9 t fresh corn and 13.02 t fodder yield ha-1), respectively. This treatment also registered significantly higher gross return (US$ 1746.9 ha-1), net return (US$ 935.8 ha-1), and benefit-cost ratio (2.15) than other nutrient management practices. Fresh cob quality in terms of protein (22.91%) and ascorbic acid content (101.6 mg 100 g-1) was observed to be significantly superior under combined application of farmyard manure (6 t ha-1) + vermicompost (2 t ha-1) than those of other nutrient management systems. However, fresh baby corn cobs produced with vermicompost 4 t ha-1 had the highest concentration of phosphorus, potassium, iron, and zinc. Application of farmyard manure 12 t ha-1 registered the maximum increment in soil organic carbon content (1.52%), its pool (40.6 t ha-1) and carbon sequestration rate (0.74 t ha-1 year-1) followed by integrated application of farmyard manure (6 t ha-1) and vermicompost (2 t ha-1). The maximum soil microbial biomass carbon and enzymatic activities [dehydrogenase (22.1 µg TPF g-1 soil h-1) and fluorescein diacetate (67.1 µg FDA g-1 soil h-1)] were noted with the combined use of farmyard manure (6 t ha-1) + vermicompost (2 t ha-1). Thus, the study suggests that the broad bed and furrow land configuration along with the combined application of farmyard manure + vermicompost could be an economically feasible practice for quality organic baby corn production and soil health improvement in the Eastern Himalaya and other similar eco-regions elsewhere.

Designing energy-efficient, economically sustainable and environmentally safe cropping system for the rainfed maize-fallow land of the Eastern Himalayas.

Achieving a circular economic model in agriculture and meeting the food requirement of the growing population is a global challenge. The task is much more daunting in the Eastern Himalaya where low productive maize-fallow is a predominant production system. To enhance system productivity and energy use efficiency while maintaining environmental sustainability and economic profitability, therefore, energy-efficient, low carbon footprint (CF; CO2-e) and profitable short duration crops must be made an integral part of the maize fallow system. Thus, six cropping systems viz., maize-fallow, maize-French bean, maize-soybean, maize-black gram, maize-green gram, and maize-toria were evaluated for seven consecutive years (2011-2018) to assess their energy requirement and efficiency, carbon footprint (CF; CO2-e), economic returns and eco-efficiency. The results revealed that the maize-French bean system had the highest system productivity (11.4 Mg ha-1), energy productivity (17.9), energy profitability (15.9) and non-renewable energy use efficiency (9.97). The maize-French bean system had also the highest net profit (US$ 3764.5 ha-1) and benefit to cost ratio (2.54). The energy consumed under different inputs/activities across the cropping systems for chemical fertilizers, diesel and machinery ranged from 50.0-62.7%, 17.3-20.8% and 4.6-15.4%, respectively. The maize-fallow system had the highest CF (0.34 kg CO2 e per kg grain) while, the maize-French bean system had the lowest CF (0.19 kg CO2 e per kg grain). The maize-French bean system had also considerably increased eco-efficiency both in terms of energy use (US$ 0.23 MJ-1) and (US$ 1.78 per kg CO2 e) over maize-fallow system. Thus, the study has suggested that maize-French bean system is energy-efficient, economically viable and environmentally safer systems to utilize maize fallow and improve food security, may help in achieving green/circular economy.