NUTRIENT MANAGEMENT IN DUAL-USE WHEAT PRODUCTION

Transcription

1 232 Southern Conservtion Systems Conference, Amrillo TX, June 26-28, 6 NUTRIENT MANAGEMENT IN DUAL-USE WHEAT PRODUCTION John Sij 1* nd Kurt Lemon 1 1 Texs Agriculturl Experiment Sttion, P.O. Box 1658, Vernon, TX *Corresponding uthor s e-mil ddress: jsij@g.tmu.edu INTRODUCTION Conservtion of our region s nturl resources is mjor priority t the highest levels of government. Conserving those resources is essentil to long-term viility of rurl economies. Crop residue on the soil surfce is eneficil in terms of reduced soil erosion, rinfll cpture, rinfll retention, nd seedling protection. Producers in this re hve not dopted no-till in grzing system ecuse of uncertinties out stnd estlishment, soil compction, soil fertility, lck of proper equipment, nd weed control. Understndly, most do not wnt to risk their future on n unproven technology. However, few producers hve successfully implemented no-till mngement in grin-only systems. The Texs Rolling Plins hs very lrge nd diverse whet/stocker opertions which rurl economies depend on s mjor source of revenue. In these systems, whet is plnted in Septemer under conventionl tillge. Numerous field opertions with lrge, expensive equipment long with high operting nd lor costs re required to prepre clen fields prior to seeding. Unfortuntely, soil moisture is lost in the process. Soil erosion y wind nd wter cn cuse significnt dmge on exposed soil. Whet seedlings re unprotected from desiccting wind nd wshing out under conventionl tillge. Lrge res re suject to replnting, creting costly delys in whet estlishment nd plnt growth needed in grze-nd-grin whet/stocker system. Conservtion tillge (e.g. no-till) holds promise in mitigting soil nd moisture losses in whet/stocker systems through incresed soil orgnic mtter, enhnced cpture nd retention of limited precipittion nd decresed risk of reseeding. Fertilizer requirements in conservtion tillge systems for whet nd stocker cttle production in the Rolling Plins re reltively unknown. A high reserch priority hs een plced on no-till nd reduced-till systems in dul-purpose whet/stocker enterprise, prticulrly development of efficient nitrogen (N) nd phosphorus fertility progrms. A key input to ll whet production is N fertilizer. Informtion on N fertility response of whet in no-till grzing system does not exist, lthough this knowledge is vitl to successful implementtion of no-till grzing systems. Our current reserch indictes tht stnd estlishment in no-till systems cn e successful with the proper equipment. Furthermore, soil compction my not e s serious s previously elieved, s long s resonle mount of residue is mintined on the soil surfce to cushion hoof ction nd the impcting effect of rin. It my tke severl yers for new production system to stilize, prticulrly when converting from conventionl tillge to conservtion tillge system. The primry ojective of this reserch is to identify N fertility levels tht mximize forge nd eef yields s well s mintining grin yield nd qulity in no-till nd conventionl-till whet/stocker production systems.

2 Southern Conservtion Systems Conference, Amrillo TX, June 26-28, MATERIALS AND METHODS The reserch site is locted out 1 miles south of the Vernon Reserch Center on the Smith/Wlker reserch unit. Approximtely 55 cres re devoted to whet, forge, nd stocker cttle reserch. Pstures re ner commercil production size (25 to 35 cres) with individul wtering sources. Studies re conducted under drylnd conditions. The soil is cly lom nd prone to wind nd wter erosion when left re. One N fertility study ws nested in lrger 35-cre psture with free-rnging stocker cttle (4 to 5 weights). Plots size ws ft y 1 ft. All fertilizer ws surfced pplied s liquid mteril. Fertilizer tretments in ech tillge system (no-till nd conventionl-till) included, 3, 6, 9, nd 1 l N/c, with nd without 45 ls N/c top-dressed in Jnury in rndomized complete lock design with 4 replictions. The Cutter whet vriety ws plnted mid-septemer t 6 ls seed/c. No-till plots were kept weed free with hericides. In August of ech yer, soils were smpled to the 2-foot depth for nitrte determintion. Plots were clipped periodiclly to determine forge production. Cttle were removed (pulled-off) from pstures when whet reched the first hollow stem growth stge to llow grin production. Whet ws mchine-hrvested for grin yield. RESULTS AND DISCUSSION Forge production in 3 to Ferury 4 ws virtully non-existent due to record dry wether from Novemer 3 through Jnury 4. Therefore, these dt re not presented. Rinfll in the fll of 4 resulted in more norml forge production (Fig.1). There ws no significnt difference (P >.5) in forge production to Mrch 1, 5 etween conventionl tillge nd no-till production system. This is promising from whet stocker grzing stndpoint. Incresing mounts of pre-plnt N resulted (P >.5) in incresing mounts of forge (Fig. 1). Forge Production to Mrch 1, 5 Forge production (l/c) NS Forge production (l/c) c c Conv-till No-till N 3 N 6 N 9 N 1 N Tillge System Preplnt Nitrogen Figure 1. Whet forge response to tillge nd preplnt N.

3 234 Southern Conservtion Systems Conference, Amrillo TX, June 26-28, 6 Tle 1 shows tht mong ll min effects nd interctions, only top-dressed N significntly influenced gin yield (P <.5) oth yers. Tillge nd pre-tretment N were significnt in 4 ut not in 5. The fct tht tillge x N nd tillge x top-dressed N interctions were not significnt indictes tht, over time nd with proper mngement, chnging from conventionltill to no-till system my not result in reduced grin yield in dul-use whet system. These results must e considered preliminry, however. Anlysis of Vrince for Grin Yield 4 5 Source DF ---Pro (F)-- Rep Tillge (T) Nitrogen (N) T x N Top-dress (TD) 1.1. TD x T TD x N TD x T x N Tle 1. ANOVA for whet grin yield. Results show tht tillge my hve some ffect on whet yield (Fig. 2). Yields were significntly higher with conventionl tillge thn with no-till in 4 ut not in 5, lthough grin yield ws numericlly less under no-till in 5. Additionl reserch will e needed to verify the effect of tillge on grin yield in dul-use system. Reduced income from slight yield reduction my e offset y the incresed cost of estlishing the whet crop under conventionl tillge. Whet Yields A 6 5 A u / c 4 3 A 4 3 B 1 1 Conv-till No-till N 45 N Top-dressed N Tretments Figure 2. Effect of tillge nd top-dressing N on whet yields.

4 Southern Conservtion Systems Conference, Amrillo TX, June 26-28, Top-dressing N significntly incresed yield oth yers of the study, ut to greter extent in 5 (Fig. 2). It ppers tht in 5, no mtter wht level of pre-plnt N the plots received, topdressing 45 l N/c mximized finl yield (Fig. 3). It should e recognized tht the sme N tretment ws plced on the sme plot in 4 nd 5. Figure 3 lso shows tht the gretest increse in grin yield in 5 occurred when N ws top-dressed on plots tht received no preplnt N. From grin production stndpoint, this system my e most economicl. However, from forge stndpoint, pre-plnt N is essentil in dul-use system (Fig. 1). Whet Grin Yields 6 5 N Top-dress '4 45 N Top-dress '4 N Top-dress '5 45 N Top-dress ' u /A N Tretments 9 1 Figure 3. Effect of N tretments of grin yield, 4 nd 5. A preliminry economic nlysis of top-dressing N to increse grin yield ws ttempted (Fig. 4). Top-dressing N resulted in positive net return with ll pre-plnt N pplic tions, except the highest pre-plnt N rte of 1 ls N/c. Applying ll top-dressed N with zero pre-plnt N generted the highe st net return. Inputs included the cost of the liquid fe rtilizer, ppliction costs, hrvest cos ts, nd price received for the hrvested grin. Seed costs, lor, fuel, mintennce, inte rest, etc. were not included in developing the net returns.

5 236 Southern Conservtion Systems Conference, Amrillo TX, June 26-28, 6 Economics Comprison 1 1 Preplnt Top-dress Preplnt 1 Top-dress Net return ($ c -1 ) N Tretment N Tretment 1 Figure 4. Economic comprison of preplnt nd top-dressed N ppliction for grin yield. Figure 5 shows nitrtes in the top two feet of soil for the two tillge systems for 4 nd 5. There were significnt (P <.5) differences etween the two systems t different depths. In 5, there ws significntly less nitrte in the top foot of soil under no-till. Since 5 ws the wetter yer, we hypothesize tht nitrtes my hve een immoilized in the decomposition of orgnic mtter or lost through denitrifiction. Nitrte Levels in Soil 3 Conv-till No-till 3 4 1/ 5 1/ Nitrte l/ c 1 1 to 6 6 to to 24 to 6 6 to to 24 1/ Smples tken in August ech yer efore ppliction of tretments Tillge systems with different letters re significntly different t P<.5. Figure 5. Soil nitrte levels in the upper 2 feet of soil under two tillge systems.

6 Southern Conservtion Systems Conference, Amrillo TX, June 26-28, CONCLUSIONS The pst two growing sesons were quite different with 3-4 eing extremely dry nd 4-5 eing normlly wet in the fll nd erly winter. Consequently, fll forge production nd grin yields were much higher in 5. In 5 there ws no significnt difference etween tillge systems with respect to forge production to Mrch 1, the generl cttle pull-off dte. Forge production nd grin yield hd ner liner response to pre-plnt N ppliction. Top-dressing 45 l N/c resulted in significnt increse in grin yield t ll preplnt N ppliction levels except t the highest pre-plnt ppliction of 1 l N/c. Grin yields in 4 were significntly higher with conv-till compred with no-till. However, in the second yer of the study, grin yields from conv- till were numericlly, ut not significntly (P =.22), superior to those from no-tillge. In 5, top-dressed ppliction of 45 l N/c resulted in mximum grin yield in ll plots regrdless of the pre-plnt N tretment. This ws less evident in 4. From grin production stnd point, the gretest yield increse occurred when 45 l N/c ws pplied to plots tht received no pre-plnt N, nd those plots lso generted the highest economic net return. The economics of eef production were not included in this study. Forge yield to Mrch 1 ws miniml in plots receiving no N, nd in dul-use system, this would not e cceptle. We re developing mngement progrms tht ttempt to find the optimum economic lnce etween forge production, grin yield, eef production, nd reduced niml helth risk. ACKNOWLEDGMENTS The uthors wish to thnk the Fluid Fertilizer Foundtion, the Potsh nd Phosphte Institute, nd the Texs Whet Producers Bord for finncil nd in-kind support of this reserch.