FAQ: Irrigation

50. How should farmers prepare check basins for efficient water application in no-till fields?
Farmers can use disk type bund maker (boarder harrow) to make check basin irrigating the wheat crop by surface flooding methods. In permanent no-till plots farmers can retain these bunds for next season. When no-till system is practiced in combination with controlled traffic, there is no need to make bunds or check basin. With controlled traffic, tramlines serve as irrigation channel due to continued compaction by tractor.

51. Does ZT wheat require same number of irrigations as in conventional plowed fields?
The crop water requirements often do not change much with planting method and are determined by several factors including crop season evaporative water demands, crop growth and phenology and nature of the soils. For optimum crop yields, it is best to apply light and frequent irrigation. With flood irrigation method, the minimum water that can be applied in fields is about 5cm/ha .Therefore, with more efficient irrigation methods, number of irrigations can be increased such as to supply same total water in small parcels to increase water use efficiency.

52. Do soil profile remain dry due reduced intake of water in zero-till system ?
Farmers practice zero-till system in two ways- i) planting a crop after complete removal or burning of the residues of the preceding crop, and ii) partial burning and removal of residues partially. In the presence of anchored or loose stubbles, usually 3-4 tons/ha, crop residues act as surface mulch, reducing evaporation losses, thereby improving the profile soil moisture storage for a longer time period.

53. Would no-till rice-wheat system benefit ground water recharge?
Rice is generally grown as a puddled transplanted crop. Puddling destroys structure, and increases compaction such as to reduce the deep percolation of water vis-à-vis aquifer recharge. In no-till rice-wheat system, rice seedlings are transplanted in the slits opened with zero-till drills, thus obviating the need for puddling and hence facilitating greater ground water recharge.

54. Is pre-sowing irrigation needed for ZT wheat?
Normally, when wheat crop preceding rice is seeded timely, the residual soil moisture is sufficient for germination to take place. If residual soil moisture is less, it is better to seed in dry soil at shallow depth and immediately go for a light irrigation. Pre-sowing irrigation help weeds to germinate ahead of main crop, make shallow tillage necessary for control of weeds. If weeds are no problem and there is still time for seeding, pre-irrigation can be applied.

55. What is the appropriate time for first pre-sowing irrigation in zero-till wheat ?
If the wheat crop preceding rice is seeded timely with sufficient soil moisture, there is no need to change the irrigation schedule 21 days after seeding. Irrigation water reduces resistance of soil to penetration of plant roots in no- till plot. Therefore, it is better to advance the first irrigation by 4-7 days (two weeks after sowing of wheat) .

56. Does advancing first irrigation in any way help germination of un-germinated seed?
Whenever, crop is planted at suboptimal soil moisture, seed are unable to germinate. Advancing first irrigation, provide soil moisture needed for germination sooner. It thus, helps farmers attain good plant population needed for good plant yields.

57. Will first irrigation in unplowed and mulched fields in any way help the percolation of water/saving of water?
In unplowed fields irrigation water spreads quickly with the result that less water is applied in irrigation. In zero-till planted wheat, about 1000m3 ha-1 of irrigation water is saved due to planting in residual moisture of rice crop and application of a light first irrigation.