This document summarizes several issues related to nutrient and water management in rice-wheat systems. It discusses low fertilizer use efficiencies, depletion of soil nutrients, emerging nutrient deficiencies, loss of soil organic matter, and inefficient water management in rice. It provides approaches to improve nutrient and water use efficiency through tools like leaf color charts and recommends best practices like laser land leveling, shallow intermittent irrigation for rice, optimizing rice planting dates, and direct drilling of wheat.

1. Nutrient and Water Management in Rice-Wheat Systems - some current issues Bijay Singh Department of Soils Punjab Agricultural University Ludhiana 141 004 Punjab

6. Leaf color charts

8. Real-time N management 2) Monitor leaf color Basal – 14 DAT or 21 DAS 1) Apply N early Plant N uptake Days after transplanting (DAT) or sowing (DAS) Monitor leaf color at 7-10 day intervals LCC reading below critical value 3) Apply N when LCC reading is below critical value

9. Fixed time – adjustable dose N management  RTOP 2004 Plant N uptake Days after transplanting (DAT) or sowing (DAS) Critical stages for N application Monitor leaf color at critical stages 3) Adjust N dose up or down based on LCC reading Basal – 14 DAT or 21 DAS 1) Apply early N Tillering Panicle initiation Heading 2) Topdress N at predetermined critical times (growth stages)

10. Grain yields of rice and wheat (nine-year average) and total P input-output balance for different P management strategies

11. Grain yields of rice and wheat (ten-year average) and total K input-output balance for different K management strategies Average K input from irrigation water: 100 kg K/ha/year K applied, kg K 2 O/ha Grain yield, t/ha K accumulation, kg K/ha Total K input-output balance, kg K/ha Rice Wheat Rice Wheat Rice Wheat 0 30 60 90 0 30 60 90 5.50 5.62 5.76 5.74 4.78 5.04 5.16 5.05 143 165 173 165 75 91 91 93 -115 -102 - 61 - 3

15. In the coming decades, a major issue in designing sustainable agricultural system will be the management of soil organic matter and rational use of organic inputs such as animal manures, crop residues, green manures, sewage sludge and food industry wastes

17. Fertilizer N equivalents FYM in rice - 42 to 52% of the total N applied Poultry manure for rice - 80 to 127%

31. Thanks!