Agronomic and Environmental Determinants of Direct Seeded Rice in South Asia

Abstract

Rice ( Oryza sativa L.) is the staple food of more than 50% of the world’s population. Manual puddled transplanted rice (PTR) system is still the predominant method of rice establishment. However, due to declining water tables, increasing water scarcity, water, labor- and energy-intensive nature of PTR, high labor wages, adverse effects of puddling on soil health and succeeding crops, and high methane emissions, this production system is becoming less profitable. These factors trigger the need for an alternative crop establishment method. The direct-seeded rice (DSR) technique is gaining popularity because of its low input demand compared to PTR. It is done by sowing pre-germinated seeds in puddled soil (wet-DSR), standing water (water seeding), or dry seeding on a prepared seedbed (dry-DSR). DSR requires less water and labor (12–35%), reduces methane emissions (10–90%), improves soil physical properties, involves less drudgery and production cost (US$9–125 per hectare), and gives comparable yields. Upgraded short-duration and high-yielding varieties and efficient nutrient, weed, and resource management techniques encouraged the farmers to switch to DSR culture. However, several constraints are associated with this shift: more weeds, the emergence of weedy rice, herbicide resistance, nitrous oxide emissions, nutrient disorders, primarily N and micro-nutrients, and an increase in soil-borne pathogens lodging etc. These issues can be overcome if proper weed, water, and fertilizer management strategies are adopted. Techniques like stale bed technique, mulching, crop rotation, Sesbania co-culture, seed priming, pre-emergence and post-emergence spray, and a systematic weed monitoring program will help reduce weeds. Chemical to biotechnological methods like herbicide-resistant rice varieties and more competitive allelopathic varieties will be required for sustainable rice production. In addition, strategies like nitrification inhibitors and deep urea placement can be used to reduce N 2 O emissions. Developing site and soil-specific integrated packages will help in the broader adoption of DSR and reduce the environmental footprint of PTR. The present paper aims to identify the gaps and develop the best-bet agronomic practices and develop an integrated package of technologies for DSR, keeping in mind the advantages and constraints associated with DSR, and suggest some prospects. Eco-friendly, cost-effective DSR package offers sustainable rice production systems with fewer resources and low emissions. Graphical abstract

Influence of tillage and residue management practices on productivity, sustainability, and soil biological properties of rice-barley cropping systems in indo-gangetic plain of India

“…preserving soil health with a substantial reduction in the cost of production and minimal environmental footprints (Johansen et al, 2012;Mishra et al, 2022). Different tillage and residue retention or incorporation practices in the rice-barley cropping system had a significant effect on the productivity and soil quality in the present experiment.…”

“…Some of these are suppression of weeds during early growth, availability of micronutrients (Fe and Zn), no infestation of nematodes, etc. (Balasubramanian and Hill, 2002 ; Kumar and Ladha, 2011 ; Ismail et al, 2012 ; Chaudhary et al, 2022 ). The lower yields in RTDSR and ZTDSR in our experiment are attributed to poor plant stand and infestation of weeds during early vegetative stages (data not presented).…”

Influence of Sowing Time and Weed Management Practices on the Performance and Weed Dynamics of Direct Drum Seeded Rice

“…Thus, decreased crop-weed competition resulted in improved growth character- Significantly less population of weeds and weed dry weight were recorded in earlier sowing over delayed sowing at 30, 45, and 60 DAS and at harvest, which may have occurred due to a relatively favorable environment and weather conditions for attaining optimum germination and early plant establishment with development of more canopy offering stronger smothering potential to crops, resulting in increased weed control, which permitted crops to best use the natural resources in the area with less light transmission ratio at the surface level inhibiting weed seed germination and growth. 52,53 Herbicides were not only less hazardous to rice seedlings, but they also effectively reduced weeds. Moreover, the efficacy and long-term effectiveness of applied herbicides that prevented weeds from germinating and resulted in a rapid decline in carbohydrate reserves in weeds that had germinated due to rapid respiration reduced the leaf area and leaf senescence, leading to reduction in the photosynthesis process.…”

Irrigation Management Strategies to Increase Crop-Water Productivity and Grain Quality of Direct Seeded Rice in North West IGP: A Review

“…For direct seeded rice to provide a larger yield, fertiliser must be applied properly and on time. N should be applied in four splits (15,30,45, and 60 days after planting) for medium duration cultivars (140 d). On the basis of a soil test, fertilisers should be administered.…”