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Parthenium hysterophorus L. is considered globally as one of the most troublesome weeds, which has invaded non-cropped as well as cropped lands in many tropical and sub-tropical countries including India. Biological control using the Mexican beetle (Zygogramma bicolorata Pallister) among other agents, has been considered most successful in India. In the present study, models were developed using climatic indices (minimum temperature, maximum temperature, rainfall and relative humidity) as independent variables to determine the suitable sites for the establishment of Z. bicolorata. Regression approach for model building revealed 79.6% concordance, 20.0% discordance, and 0.4% tie between predicted probabilities and observed responses whereas, decision tree using J48 algorithm classified 81.7% instances correctly which helped to frame the rules for predicting the establishment of Z. bicolorata. Based on these rules, it was concluded that a site experiencing climate with indices values of average minimum temperature 24.2–26.2 °C and rainfall 191.2–257.3 mm during July to October would be highly suitable for setting up the Z. bicolorata population in the region. These models might be useful to decide the most suitable sites for release and establishment of Z. bicolorata in India as well as in other parts of the world with similar climatic conditions. • Parthenium hysterophorus L. is one of the most troublesome weeds globally. • Biological control of P. hysterophorus using Zygogramma bicolorata Pallister has been considered most successful in India. • Regression approach and decision tree using J48 algorithm were used to model the establishment of beetle using climatic variables. •. Minimum temperature and its interaction with rainfall and relative humidity were found to be important climatic variables • These models might be useful for the selection of most suitable sites for release and establishment of Z. bicolorata. [ABSTRACT FROM AUTHOR]

Abstract: In a study on sandy loam soil of Indian Agricultural Research Institute (IARI) farm of New Delhi, soil hydrothermal environment under bed planted wheat was compared with conventionally flat planted wheat for evaluating the suitability of bed-planting system for the semiarid climate of this region. The soil temperature and water contents of the 0–20 cm soil profile under bed and conventional planting were monitored during drying cycle after 2nd and subsequent irrigations. Results revealed that mostly soil water content under bed planting was lower by 0.5–1% (w/w) than under conventional system mainly due to lower application of irrigation water and because of more porous soil environment. But it was also noticed that by applying irrigation at 22 days interval, soil water under bed remained within the available soil water range. It was observed that under both methods of planting magnitude of the maximum temperature decreased with an increase in soil water content, but for both high and low soil water contents (SWC), the temperatures were higher by 0.5–3 °C at the surface and subsurface (up to 20 cm) under bed than under conventional flat planting. Soil temperature data collected at 2 h interval during the day to monitor the maximum soil temperature showed that magnitudes of the peak at all depths were higher in bed planting and their arrival times were also earlier than in conventional planting. Again, at low SWC, peak soil temperature at the surface was near or higher than aerial temperature and at higher SWC, it was lower than aerial temperature. For similar aerial temperatures (30 °C), with an increase in SWC, both volumetric heat capacity and thermal diffusivity increased and their magnitude on bed was lower than that on conventional planting. [Copyright &y& Elsevier]

• Unified SQI was developed after 8 years of CA through PCA using 15 soil parameters. • The ZTDSR – ZTM – ZTSMB (+R) system had highest, whereas TPR-CTM had lowest SQI. • The ZTDSR – ZTM – ZTSMB (+R) resulted in ∼14 % higher total SOC than the TPR – CTM. • The key indicators were hydraulic conductivity, pH, total N, available P and K. • CA practice maintained higher soil quality and crop yield in rice-mustard system. The systematic research on the effect of medium-term conservation agriculture (CA) on soil quality, especially under the rice (Oryza sativa L.)-based cropping systems is limited. Hence, the specific objective of the study was to develop soil quality indices with key soil physical, chemical and biological indicators under the conservation and conventional tillage practices in a rice–mustard [ Brassica juncea (L.) Czern.] cropping system. Eight treatment combinations including tillage and crop establishment, crop residue and cropping system intensification with inclusion of short duration summer mungbean [ Vigna radiata (L.) Wilczek] were adopted in rice - mustard cropping system in hot semi-arid, sub-tropical north-western Indo-Gangetic Plains agro-ecoregion of India. Soil samples collected from topsoil (0−5 cm) and 5−15 cm soil layer were analyzed for 15 physical, chemical and biological properties to develop unified soil quality index (SQI) through principal component analysis (PCA). The highest SQI was obtained in the zero till direct seeded rice (ZTDSR) – zero till mustard (ZTM) –ZT summer mungbean (ZTSMB (+R) (mungbean residue in ZTDSR - rice residue in ZTM- mustard residue in ZTSMB) treatment followed by the ZTDSR + BM (brown manuring) – ZTM (+R) (mustard residue in ZTDSR with BM – rice residue in ZTM). The lowest SQI was obtained in transplanted puddled rice (TPR) - conventional till mustard (CTM) for both soil layers. The identified key indicators for SQI in this Inceptisol were saturated hydraulic conductivity (K s), pH, total N, available P, and available K. Besides, the plots under ZTDSR – ZTM – ZTSMB (+R) resulted in 14 % higher total organic C in topsoil and 28 % higher aggregate stability than the TPR - CTM plots. This ZTDSR – ZTM -ZTSMB (+R) treatment had 65 % higher surface soil microbial biomass C than the TPR – CTM treatment. The ZTDSR – ZTM -ZTSMB (+R) treatment also led to higher K s , which was in the order of triple ZT > double ZT > ZT > conventional tillage. Thus, the medium-term CA with triple or double zero tillage with crop residue retention could lead to maintain agricultural sustainability under rice-mustard system. Hence, it may be recommended to the farmers for adoption. [ABSTRACT FROM AUTHOR]

• A CA-based DSR–mustard(M)–mungbean system gave 11 % lower rice yield than TPR-CTM. • It resulted in 30 % higher mustard yield and higher net returns than TPR-CTM system. • It gave 44 % higher system yield and 36 % higher water productivity than TPR-CTM. • It had higher very labile (50.6 %) and labile (47.7 %) carbon at 0−5 cm soil layer. • CA based practices reduced weed density in mustard than the TPR-CTM system. Developing suitable crop rotations and crop establishment practices is an important mechanism that can enhance factor productivity and sustainability of an agro-ecosystem. However, the impact of Conservation Agriculture (CA) on alternate crop rotation of the most-dominant but tillage- and input-intensive rice (Oryza sativa L.)-wheat (Triticum aestivum (L.) emend Fiori & Paol) rotation of the Indo-Gangetic Plains (IGP) of India is not elaborately studied. Hence, we evaluated the effect of CA on crop and water productivity, profitability, and soil carbon status in rice-mustard (Brassica juncea L.) rotation in the North-western IGP of India for five consecutive years. Eight treatments comprising of tillage, crop residue, brown manuring (BM) using Sesbania bispinosa , and summer mungbean [ Vigna radiata (L.) Wilczek] (SMB) were adopted in rice - mustard cropping system. The conventional transplanted puddled rice (TPR) - conventional till mustard (CTM) (∼TPR-CTM) rotation resulted in significantly higher rice grain yield than zero till direct-seeded rice (ZTDSR) – ZT mustard (ZTM) system with or without crop residue in all five years. However, in this regard, the CA-based ZT rice – mustard - SMB with residue [ZTDSR-ZTM-ZTSMB (+R)] was comparable with it during first three years, but was inferior to it in 4th and 5th years. The ZTDSR-ZTM-ZTSMB (+R) had overall 10.9 % lower five-year mean rice yield than that in the TPR-CTM system. This CA-based system gave significantly higher mustard grain yield in all the years (except first year), and the five-year mean mustard yield was 30.3 % higher than in the TPR-CTM. Another CA-based double cropping system having ZTDSR + BM – ZTM (+R) was comparable with TPR-CTM in all the years and resulted in 27.6 % higher five-year mean mustard yield than the TPR–CTM practice. The ZTDSR-ZTM-ZTSMB (+R) practice gave 44 % (including SMB) and 8.1 % (excluding SMB) higher system productivity and significantly higher sustainable yield index of the rice-mustard system compared with the TPR-CTM practice. The ZTDSR-ZTM-ZTSMB (+R) practice encountered significantly lower weed density in mustard in all five years than TPR-CTM system. The cost-benefit analysis revealed that this CA practice fetched higher net returns by INR 53,000 and 21,400 ha−1 from the rice-mustard system with and without SMB, respectively over the TPR-CTM system. Again, this ZTDSR -ZTM- ZTSMB (+R) system led to an increase in irrigation water productivity by 27.8 % in rice and 35.1 % in mustard, and the total water (irrigation + rainfall) productivity by 35.7 % in mustard crop compared with the TPR-CTM system (P ≤ 0.05). This CA-based rice-mustard system resulted in significantly higher very labile (∼50.6 %) and labile (∼47.7 %) carbon concentration at 0–5 cm depth of soil compared to the conventional TPR-CTM system. The CA system being productive, profitable, and resource-efficient can be recommended for North-western IGP of India and in similar agro-ecologies of the tropics and sub-tropics. It can be adopted with suitable site-specific refinement in South-Asian countries, where decline in crop productivity and soil health is a consistent pervasive problem due to continuous cereal-cereal rotation. [ABSTRACT FROM AUTHOR]