Can you Write a general essay on scientific farming?

Answer 1

Direct-seeded (DS) culture has become increasingly important in rice cultivation. The scarcity of rural labour coupled with escalating production costs constitute the main reason for the shift in DS rice culture and its rapid and eventual adoption from transplanting. In Malaysia, wet seeding is normally preferred. The economic incentives for adoption of wet seeding were provided for by its labor saving feature as exemplified by 1-2 man day/ha vis-a-vis ca. 20 man day/ha in the transplanting rice culture. A cardinal and perennial constraint in wet-seeded rice is weed infestation, requiring good field drainage and judicious water control for satisfactory crop establishment and weed control. Farmers practising wet seeding normally use higher seeding rates, spent more on herbicide-based weed control. Some of the factors influencing weed prevalence in rice fields include the rice culture system, soil moisture regime, crop rotation, cropping pattern, land preparation and tillage regimes, light, soil temperature, fertilizer application, rice cultivar and seeding rate, as well as weed control technology. Farm surveys assessing the magnitude and extent of weed infestations in rice-growing areas are an important step in formulating an appropriate control package. Prior to 2000, the dominance of Scirpus grossus and Marsilea crenata, were registered in major rice granaries in Malaysia although Echinochloa spp. (principally represented by E. crus-galli var. crus-galli, E. crus-galli var. formosensis, E. oryzicola,and E. colonum), Leptochloa chinensis, Fimbristylis miliacea and Sphenoclea zeylanica were highly prevalent in all seasons since 1995. The rice weed flora in the new millennium were dominated by measurable and parallel increase in infestation and population density especially the four most widespread and abundant weed recalcitrant and millennial species, viz. weedy rice (WR) or Oryza sativa complex, L. chinensis, E. crus-galli complex and Ischaemum rugosum, were consistently observed. Similar trends were also observed in Vietnam, Thailand, Sri Lanka, Korea, and the Philippines. We believe that this phenomenon resulted from continuous practice of DS culture leading with continuous season-mediated accumulation of seed bank of the named weed species. It is reasonable to argue that this might be due to no selective herbicide being available to control WR, perhaps the farmer's inability and reluctance to manually control this weed at the early stage of crop growth was possibly due to crop mimicry. On the contrary, grassy weeds like E. crus-galli complex and L. chinensis can be controlled by selective herbicides such as cyhalopfop-butyl, quinlorac, molinate, propanil, fenoxaprop-ethyl and bispyribac-sodium if applied correctly. The continuous prevalence of WR calls for effective measures against the scourge aligned with other grassy weeds as the primary target of control.

Crop losses due to weed competition vary with the duration of weed infestation. Integrated approach based on critical period (CP) for weed management in DS involving indirect- and direct control measures should be adopted. Sympatric weed species emerging with rice crop plants have an adverse effect on crop yields. Crop losses due to weed competition vary with the duration of weed infestation of the crops. Rice crop is likely to experience yield reduction unless it is kept weeds free during the CP of its growth duration, the phenomenon otherwise referred to as the CP of weed competition. Based on the predicted Logistic and Gompertz response curves the CP for WR control based on 5% yield loss was estimated from 16 to 53 days after sowing (DAS) in DS culture, or from 12 to 60 DAS under mixed weeds situation. To ensure weeds are suppressed during CP, pre-emergence herbicides are normally applied before or after crop sowing and these herbicides must have residual activity to control weeds at CP of weed competition. If early post-emergences are used, it should be applied at the onset of CP. If weeds still persist, late post-emergence herbicide treatments can be instituted at mid CP of weed competition. Manual weeding where necessary should be carried out during CP. Due to crop mimicry of WR, manual weeding is cumbersome in WR-infested fields. Alternatively, rouging of WR panicles must be done after CP to reduce seed banks of the ensuing crops.

Choice of appropriate crop establishment technique is an important step towards good agricultural practice in rice culture. Water seeding (pre-germinated rice seeds broadcast onto standing water) appears to provide a valuable alternative to the usual wet seeding culture, and this leads to improved weed control besides providing good crop establishment. Standing water used for puddling is not drained, but conserved in the field. The presence of standing water during rice establishment significantly reduced grassy weeds particularly WR and some sedges. A major limitation of this method is seed drift, but this can be avoided with proper land preparation with the following pre-requisites, viz. the land must be flat and level; and leveling must be done with furrows during final tillage for better water distribution; minimize straw residue; use extra seed rate (30% of the normal seeding rate); use pre-germinated seeds; fields must have clear standing water maintained at 5-10 cm depth; seed treatment (with growth regulator if necessary) to ensure better establishment, and the bunds are strong and not permeable. The choice of crop establishment method should be based on WR population in the previous season. If WR infestation in the previous season is less than 5 panicles/m2 conventional wet seeding technique can be practiced. This method of rice culture can be adopted if land is thoroughly prepared to reduce WR seed bank. In situations where WR populations exceeded 6 panicles/m2, water seeding technique is highly recommended. This calls for the use of certified rice crop seeds devoid of WR. Through water seeding, water can be saved, reducing unnecessary wastage compared to normal wet seeding. In the latter practice, standing excess water need to be drained before the pre-germinated seeds can be sown. A field scale exploratory study to evaluate the impact of continuous water seeding technique in an area heavily infested by WR (at 117 panicles/m2 with usual wet seeding), registered 90% reductions in WR populations (35 panicles/m2 in the first season of water seeding and 8 panicles/m2 in the ensuing season) resulting in nearly 100% increment in rice yields.