Calibrating In-field Diagnostic Tools to Improve Nitrogen Management for High Yield and High Protein Wheat in the Sacramento Valley

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1 Reserh Report to the Cliforni Whet Commission Clirting In-fiel Dignosti Tools to Improve Nitrogen Mngement for High Yiel n High Protein Whet in the Srmento Vlley PI: Mrk Luny, UC Coopertive Extension Agronomy Avisor Summry: Growers of hr n urum whet re pi not only for rop yiel ut lso for grin protein ontent. These ftors re inversely relte n eh is strongly influene y the rte n timing of nitrogen (N) fertiliztion. The eonomi implitions of this ynmi re ler: the quntity n timing of N fertiliztion shoul e optimize to proue the est omintion of whet yiel n qulity per ollr of N pplie. In orer to evelop guielines for optimum N mngement in the Srmento Vlley, the ojetives of this reserh were to: 1) Estlish multi-rte, split-pplition N fertiliztion trils on representtive vrieties of whet in the Srmento Vlley region. 2) Mesure the N sttus of the plnt-soil environment t key phenologil stges using oth lowost, in-fiel methos n estlishe reserh methos. 3) Begin to evelop eision support threshols tht relte the in-fiel ignosti metris to likely yiel n protein responses uner the vrious mngement senrios ente. The gol of this work is to equip growers n rop onsultnts with etter unerstning of the nee for N t vrious stges of rop growth n, potentilly, guielines s to pproprite rtes se on the use of in-fiel tests of the plnt-soil environment. A multi-yer reserh projet is require to hieve this gol. This oument reports on the reserh unertken uring the seson, whih ws prtilly fune y the Cliforni Whet Commission n the CDFA FREP progrm. Methos: We estlishe split rte N trils t two lotions in the Srmento Vlley. The N rte n timing, wter mngement, vrieties, n plnting n hrvest tes for these trils re etile in Tle 1. Of note n importne to the interprettion of the results is tht there were three wter mngement senrios etween the two lotions. At Fiel 1, lote on the UC Dvis reserh fiels, the rop ws irrigte to voi ny wter stress. In ition, unless suffiient rinfll followe in-seson pplitions of N, the fiel ws irrigte to ensure tht the pplie N ws fully ville to the plnt. Thus, potentil N y wter intertions were minimize t this site n it h high yiel potentil. In ontrst, Fiel 2 ws lote t the Russell Rnh long term reserh fility. One of the two trils ws lote in one-re plot tht reeive supplementl irrigtion, while the other tril ws lote in one-re plot tht reeive no supplementl irrigtion. Given the elow verge rinfll uring the seson, rops in oth trils t Fiel 2 isplye wter-efiieny symptoms t ifferent points in the seson. At Fiel 2, in-seson pplitions of N were time to preee rinfll events, n the pplitions were followe y rinfll of t lest 0.4 inhes within the susequent 2 ys. However, no irrigtion ompnie these pplitions. In ition, wee ontrol ws not optiml t Fiel 2. Thus, there ws n inrese potentil for intertions etween pplie N, wter, n wees, n n overll lower yiel potentil t Fiel 2 thn t Fiel 1. As result, with respet to Ojetive 1, this nnul report will report the results from Fiel 1. Responses to N rte n timing t Fiel 1 were nlyze vi ANOVA with men seprtions (P<0.05) onute vi LSD.test in the griole pkge of R version

2 Tle 1. Mngement etils of multi-rte, split-pplition N fertility trils for seson. Lotion Russell Rnh Cl Rojo Plnte 11/2 Hrveste 5/30 UCD Agronomy Ptwin Plnte 11/15 Hrveste 6/9 Irrigtion None Supplementl Fully irrigte Fertility PREPLANT TILLERING BOOT FLOWERING TOTAL tretment N fertilizer pplie (l/re) As is emonstrte n isusse in the Results & Disussion setion, the vrying egrees of yiel potentil n soil wter vilility etween Fiels 1 n 2 provie vlule opportunity to test the sensitivity of the in-fiel N ignosti tools to heterogeneous growing environments. The suite of infiel tests we eploye is reporte in Tle 2. Of these, the olorimetri proximl sensing evies (AtLef; Greenseeker), whih mesure light refletne from the leves n nopy in the visile n ner infrre spetrums, provie the most vlule informtion. As suh, our lirtion efforts hve een onentrte on these mesurements to te. The AtLef hlorophyll meter (Imge A) is SPAD proxy mesuring refletne from lef smple t 660nm n 940nm. At the vrious stges of potentil N pplition (tillering, oot, n flowering) the AtLef inex of 20 penultimte leves ws mesure from selete N tretments. Likewise, the Greenseeker hnhel NDVI meter (Imge B) ws use to mesure refletne 2-3 feet ove the nopy uring these rop growth stges. Soil n tissue smples were lso tken t the vrious in-seson smpling stges n will e useful in orroorting the mesurements from the in-fiel tools. In ition, the itionl plnt-soil informtion ollete my eome more vlule s we site-yers to the tset euse it oul serve to orret for etween-site vriility in se fertility. However, with respet to Ojetive 2 n 3, this nnul report

3 will fous on the potentil for the AtLef n Greenseeker tools to inite yiel n protein responses to N fertiliztion n timing. This ws nlyze vi mixe, non-liner regression proeures (nlme pkge in R 3.0.2) where the meter reing for given plot t given stge ws fit vi liner plteu moel to N fertilizer pplie t tht stge, n lso to the protein (AtLef) or protein yiel (Greenseeker) result. The resulting threshols were then pplie vi inry lssifition to the evelopment tset. The resulting mein vlues n ssoite vriles were susequently plotte vi oxplots. Tle 2. In-fiel ignosti tests eploye t vrious stges of whet evelopment. Crop stge In-fiel Methos Soil C preplnt tillering oot/flowering Solvit, POX-C Soil N nitrte Soil N nitrte Soil N nitrte Plnt N Yiel Potentil AtLef (SPAD proxy) Greenseeker (NDVI) Fiel Sout (DGCI) Lef sp nitrte LAI lef imensions Plnt N Yiel Potentil AtLef (SPAD proxy) Greenseeker (NDVI) Fiel Sout (DGCI) lef imensions For the t urrently ompile, the flowering-stge metris re most emonstrtive of the potentil vlue of the in-fiel tools n re therefore reporte here. The sme pprohes re eing use to nlyze oot n tillering stge t ollete in the Srmento Vlley. In ition, in-seson mesurements were tken t the Intermountin REC for the tillering, oot n flowering stges, n t Westsie REC for the tillering stge. These t will e eventully inorporte into the eventul multiyer, multi-site nlysis, ut re not reporte on here. Imge A. AtLef hlorophyll meter. Imge B. Greenseeker hnhel NDVI meter.

4 Results & Disussion: Yiel, protein, protein yiel n Nitrogen use effiieny responses to multi-rte, split-pplition N fertiliztion Prior to estlishment of the whet rop, Fiel 1 h een mnge with the ojetive of epleting ville soil N (two sungrss rops n one whet rop tht h reeive no N fertiliztion). As result, initil soil nitrte-n vlues were less thn or equl to 1.5 ppm NO3-N in the first 8 feet of the soil profile. The omintion of low ville soil N n high yiel potentil resulte in strong yiel n protein responses to N fertiliztion (P<0.01), with the ontrol (zero N) resulting in 40%- 60% of the mximum yiel, protein n protein yiel (Figure 1). For N rtes split etween preplnt n tillering (the most ommon urrent mngement prtie), yiels inrese up to 150 l N re 1 (Figure 1), protein yiels inrese up to 225 l N re 1 (Figure 1), n protein inrese up to 300 l N re 1 (Figure 1). Among yiel-mximizing rtes, the 150 l N re 1 tretment use N more effiiently thn the 300 l N re 1 tretment n ws lso trening higher in N use effiieny thn the 225 l N re 1 tretment (Figure 1). It is importnt to note tht the omintion of higher thn verge yiels n extreme soil N efiieny oserve in this tril rete onitions for N responses t rtes higher thn re typilly use for whet in the Srmento Vlley. Therefore, we shoul not neessrily onlue tht the solute rtes reporte here re visle uner norml mngement onitions. In ition, the results reporte in Figure 1 re for N fertilizer split-pplie preplnt n t tillering. Yet, intertions were mesure etween the timing of N n the solute N rte (P<0.01). As suh, higher or lower N rtes woul e require, epening on the pplition timing. However, it oes pper tht rtes in exess of 150 l N re 1 my e visle uner some irumstnes in orer to meet yiel n protein gols. As more site-yers re e to this stuy, we will e le to isern solute N requirements with inresing onfiene. Yiel, protein, protein yiel n N use effiieny outomes were lso ffete (P<0.01) y the timing of N fertiliztion. Of note is tht, for N rtes 225 l N re 1, preplnt N pplitions were lest effetive from yiel, protein, protein yiel n NUE perspetives (Figure 2). Inee, tretments tht reeive no N fertiliztion until tillering h the est protein, protein yiel n NUE outomes (Figure 2). This is surprising result given tht plnts whih h reeive no preplnt fertiliztion ppere N- efiient oth visully n oring to the in-fiel plnt n soil mesurements tken t tillering. While the mehnism for this response is not yet ler, it is possile tht the erly-seson efiieny omine with suen unne of ville nitrogen results in ompenstory growth tht uils yiel omponents more effiiently thn if plnt h reeive N fertiliztion preplnt. In ition to tillering vs preplnt ifferenes, flowering pplitions resulte in higher protein thn oot pplitions for N rtes of 150 l N re 1 ut not for rtes of N rtes of 225 l N re 1 (Figure 2 epits omintion of 150 n 225 l N re 1 rtes). Tken together, the results from the initil yer of experimenttion suggest tht N fertilizer timing t tillering n flowering my proue the est proutivity n effiieny outomes. However, for growers, the logistil fesiility of these preise timings epens on wter vilility n fertilizer elivery options. In ition, these results must e ross-vlite with the t ollete t other sites n using other vrieties.

5 Protein yiel (l/re) N use effiieny Yiel (l/re) Protein (%) Yiel. Protein e N rte (l/re) N rte (l/re) Protein yiel.. N use effiieny N rte (l/re) N rte (l/re) Figure 1. Yiel, protein, protein yiel n N use effiieny s result of vritions in N fertilizer rtes in the preplnt-tillering split rte tretment in Fiel 1.

6 Protein yiel (l/re) Till+Boot+Flower Pre+Till+Flower Pre+Till+Boot Pre+Flower Pre+Till Pre N use effiieny Till+Boot+Flower Pre+Till+Flower Pre+Till+Boot Pre+Flower Pre+Till Pre Protein (%) Till+Boot+Flower Pre+Till+Flower Pre+Flower Pre+Till+Boot Pre+Till Pre Yiel (l/re) Till+Boot+Flower Pre+Till+Flower Pre+Till+Boot Pre+Till Pre Pre+Flower Yiel. Protein. N fertilizer timing Protein yiel N fertilizer timing N use effiieny.. N fertilizer timing N fertilizer timing Figure 2. Yiel, protein, protein yiel n N use effiieny s result of vritions in N fertilizer timing for 150 l N re -1 n 225 l N re -1 tretments in Fiel 1.

7 Greenseeker NDVI n AtLef hlorophyll inex s preitors of protein & protein yiel outomes The AtLef hlorophyll meter n the Greenseeker hnhel NDVI meter provie istint n omplementry informtion out the N sttus of the rop. When regresse ginst the pplie N rte, the AtLef inex ws more sensitive initor of lef N sttus. This n e oserve y noting the higher verge lef hlorophyll inex in the unirrigte vs supplementlly-irrigte whet in Fiel 2 (Figure 3). Here, the whet in the unirrigte plot h less yiel potentil ue to reltively greter wter stress. As result, for n equivlent N rte (100 l N re -1, for exmple) we woul expet the tissue N to e more onentrte. Inee, in Fiel 2 the AtLef inex ws higher for unirrigte thn irrigte plots t 100 l N re -1 n overll (P<0.05) t oth oot n flowering stges. Although the lortory tissue results hve not een omplete, we expet them to orrelte losely with the AtLef meter reings s hs een shown previously with this evie n the SPAD hlorophyll meter. Figure 3. Liner plteu threshol moels pplie to Greenseeker NDVI n AtLef hlorophyll inex mesurements tken t the flowering stge of evelopment for plots tht i not reeive susequent pplition of N. Mesurements were me t two fiels n uner three wter mngement senrios.

8 The reltive tissue N onentrtion is useful initor of the present N sttus of the plnt. However, sine the tissue onentrtion hnges over time, the plnt N sttus provies only prt of the overll piture of rop N emn. In orer to etermine whether or not to pply N fertilizer t given point in the seson, it is eqully importnt to e le to preit future N emn. Although the Greenseeker hnhel NDVI provie less preise nswer regring the onentrtion of given lef, it provie more integrte piture of the nopy N sttus. For exmple, for equivlent N rtes, the NDVI reings in Fiel 1 were onsistently higher thn the NDVI reings in Fiel 2 (Figure 3). As mentione in the Methos setion the rops in Fiel 2 h wter, wee n other mngement-relte issues tht limite yiel potentil reltive to Fiel 1. The Greenseeker NDVI ws le to inite these ifferenes t oth oot n flowering. As result, the Greenseeker NDVI ppers to e etter initor of the overll protein yiel potentil thn the AtLef inex. The regressions of Greenseeker NDVI n protein yiel (Figure 3) n AtLef hlorophyll inex n protein onentrtion (Figure 3) support the onlusions out the reltive sensitivity n preision of these in-fiel instruments. The threshols evelope vi liner plteu moels inite the meter reings eyon whih protein yiel (Figure 3) or protein onentrtion (Figure 3) responses re not expete t the flowering stge. Sine the meters pper to provie istint informtion out the onentrtion of n overll emn for N, these threshols my e most informtive when use in omintion. For exmple, the L L omintion in Figure 4 inites plots where oth Greenseeker n AtLef reings were elow the threshol vlues, mening tht oth the reltive tissue N onentrtion n reltive protein yiel potentil were low. In this senrio, the flowering pplition of N (L L Y) i not inrese protein onentrtion euse the future emn for itionl N ws insuffiient (Figure 4). In ontrst, the H L omintion inite tht the Greenseeker reing ws higher thn the threshol n the AtLef reing ws lower thn the threshol. In this senrio, there ws likely enough reltive yiel potentil for the rop to respon to itionl N uring grin filling. Therefore, plots tht reeive flowering pplition of N (H L Y) resulte in higher protein thn plots tht i not (H L N) (Figure 4). In omintion, the two meters threshols pper to more urtely preit protein responses in this intermeite protein rnge thn either meter threshol ws le to on its own. From prtil perspetive, the omine use of these in-fiel sensing evies longsie ppropritely lirte threshols my e le to proue tionle, in-seson N mngement reommentions for Cliforni whet growers. However, these onlusions shoul e onsiere tenttive t this stge given the quntity of t n the ft tht the results prtilly esrie the sme t from whih the threshols were erive. Aitionlly, there is strong possiility for the threshols to vry oring to ultivr n limte. To ount for these potentil intertions, t ws ollete uring the seson t oth the Intermountin n Westsie RECs for ifferent ultivrs thn those mesure in the Srmento Vlley. However, this t hs not yet een inorporte into the nlysis reporte here. Therefore, further nlysis of the t n further t olletion in will e require in orer improve our onfiene in these onlusions.

9 Figure 4. Boxplots of protein yiel, yiel, protein onentrtion n N use effiieny s etermine y inry lssifition for omintions of Greenseeker n AtLef vlues ove (H) or elow (L) threshol vlues reporte in Figure 3 n 3 tht either i (Y) or i not (N) reeive flowering pplition of N.

10 Buget summry Buget for Cliforni Whet Commission Grnt Title: Clirting In-fiel Dignosti Tools to Improve Nitrogen Mngement for High Yiel n High Protein Whet in the Srmento Vlley PI: Mrk Luny Ctegory Projete ($) Atul ($) Pening ($) Desription/Notes Fiel Supplies n Equipment 2000 fertilizers; ertifie see; stkes, flgs, gs, mis supplies Servies 500 Deep ore soil smpling to 8' on suset of plots 0 hrge to nother ount to offset itionl l hrges Plnt n Soil Anlysis 4610 nlytil l fees (soil n plnt N) itionl smpling t Intermountin REC, whih ws eyon sope of propose osts; AN L fees inrese pproximtely 20% Anlytil Supplies 1000 one-time use nlytil tests/tools remining inventory will e use in work Anlytil Equipment 2000 reusle mesurement evies prtil osts; reminer hrge to ifferent ount to offset itionl lortory osts Totl = 10110