Viljelussüsteemide mõju kartuli mugulasaagile ja kvaliteedile

A Thesis for applying for the degree of Doctor of Philosophy in AgricultureThe world’s population is estimated to exceed over 9 billion people by 2050 (FAO, 2013), thus the demand for high yielding, good quality crops as well as the “challenges for the sustainability of the ecosystems” increases (Somers and Savard, 2015). Proper crop management is a key element in achieving high yields of good quality. Crop rotation, animal manures, and winter cover crops as catch crops (CC) play important roles in sustainable plant production systems because they provide nutrients for the system (Stark and Porter, 2005). CC and animal manures are mainly used by organic producers, because these are the main nutrient-rich sources for organic crop production. Animal manures are used by conventional producers only if, in addition to crop production, they have also livestock. Conventional producers, who grow only crops, largely depend on mineral fertilizers and different synthetic agrochemicals. According to Luik et al. (2008) conventional systems might not be sustainable in the long term, because they tend to be oversimplifi ed and maximally intensifi ed. But Edwards-Jones and Howells (2001) claimed that neither conventional nor organic farming systems (FS) are sustainable because both of them require inputs from non-renewable resources and, one way or another, they both impact on the environment. For organic producers there are also two main challenges, such as managing diseases and nutrients since nutrient availability is limited and there are only a few effective pesticides available that are allowed for use (Finckh et al., 2006). Also, Nelson et al. (2009) confi rm that in organic systems nutrient transformations almost exclusively relyon soil. In conventional systems, if there are problems with diseases or pest and with plant malnutrition, synthetic agrochemicals and mineral fertilizers can be provided throughout almost the entire growing season. Despite some limitations in organic farming, organic agriculture is based on its own self-regulating production system, and the concept of a farm is as an agro-ecosystem (Lammerts van Bueren et al., 2002). But organic agriculture alone does not provide a suffi cient amount of food for the growing population (Oliver and Gregory, 2015). In contrast, conventional agriculture depends mainly on external inputs, which makes it somewhat more vulnerable. To consider farming systems to be sustainable they must be “productive and maintain their contribution to society in the long term” (Gadanakis et al., 2015). In general, the demand for agricultural practices and food security that are more environmentfriendly is increasing rapidly, which favours the development of new 10 integrated farming systems (Duc et al., 2015). Such farming systems that use integrated management practices, such as crop rotations and organic (green manure crops, leguminous crops, CC) and inorganic fertilizers, will maintain soil as well as human health (Marsh, 2000; Oliver and Gregory, 2015). Future agriculture must also evolve towards climate-smart agriculture technologies, which are more adaptive to climate change by improving resource use effi ciency and ensuring food security (Zhang et al., 2015). Achieving food security does not only mean an adequate food supply but it also means that the food must be nutritious, of good quality (Wei et al., 2015). The potato is one of the most important crops worldwide, ranking fourth in annual production (Fernie and Willmitzer, 2001). The potato can be grown in harsher climates, and it is able to give, relatively quickly, high nutritious yields compared to any of the other major food crops (Lutaladio and Castaldi, 2009). However, to be productive, the potato needs signifi cant nutrient inputs to maintain its productiveness and quality. Crop management is the main factor that infl uences crop production and disease resistance (Larkin and Halloran, 2014; Olanya et al., 2014). Previous research has shown that FS affect tuber quality characteristics such as tuber nutrients (Järvan and Edesi, 2009) as well as starch and dry matter (DM) contents (Roinila et al., 2003). Plant nutrition is an important factor that infl uences natural disease resistance. If there is a defi ciency of essential elements susceptibility to potato diseases increases (Czajkowski et al., 2011), because the plant’s natural ability to fi ght them is lowered (Mulder and Turkensteen, 2005). Nutrients affect the plant physiology and thus potential for infection with pathogens (Dordas, 2008). At the European Association for Potato Research (EAPR, 2014) conference last year it was concluded that the agronomy side of potato production has gained too little attention over the past years and needs to regain its importance, because the agronomic side of potato production determines the potato performance parameters. Potato is a crop that has been studied in Estonia extensively because of its importance in Estonians everyday diet. The fi rst true Estonian potato scientist was Julius Aamisepp who promoted the cultivation of potato and its research. The fi rst fertilization experiments were conducted by Arnold Piho in 1960–1980 which also included the potato crop. The latest potato fertilization research has been made by Kuldkepp et al. 11 (1999), by Astover and Roostalu (2003), by Järvan and Edesi (2009), by Toomsoo and Leedu (2002), by Toomsoo et al. (2009; 2012). However, such complex potato fertilization research (under different organic and conventional farming systems) presented in current thesis has not been made before in Estonia. Earlier potato research has had mainly domestic importance. In the past, besides potato fertilization, the effect of different potato pre-planting thermal treatments on the tuber yield formation has been studied by Viacheslav Eremeev. Also there has been some potato disease related research by Mati Koppel who studied the potato soft rot (Erwinia/Pectobacterium spp.) disease and by Eve Runno-Paurson who investigated the potato late blight (Phytophthora infestans). The potato meristem multiplication has been studied by Viive Rosenberg and Marje Särekanno. Potato research related to plant breeding has been conducted by Aide Tsahkna and Mati Koppel. There are many other great potato researchers in Estonia who are a true experts in their fi eld of study. Crop rotations are important tools that affect potato productivity (Carter et al., 2003) and diseases (Peters et al., 2004). Catch crops are essential to avoid nutrient losses (Stark and Porter, 2005). Brassica crops used as CC have, furthermore, been found to have a disease suppressing effect (Cohen et al., 2005). Since the potato is a high nutrient demanding crop, additional mineral or organic fertilizers must be provided. Despite nitrogen (N) being a basic potato nutrient, the selection of its appropriate application rate for the potato is quite diffi cult, due to signifi cant variation (Zebarth et al., 2009). The appropriate N demand can vary among many factors such as climatic conditions during the growth period, crop management practices the previous crops cultivated. Addressing all the aforementioned factors should ensure high potato yields of good quality. Currently, these are the following gaps in our knowledge: (i) how the yield increase through different agronomic practices affects the potato tuber mineral elements concentrations (which are considered tuber nutrients) (White et al., 2009) and overall crop quality (Wang et al., 2008), (ii) how crop rotations infl uence tuber quality parameters (Mohr et al., 2011), and (iii) how the plant nutrition and crop rotations together affect the occurrence of tuber diseases (VanderZaag, 2010). The focus of much research tends to be on organic or conventional management systems separately, it is important to investigate their infl uence together comparatively (Bernard et al., 2014). Thus, the overall aim of this thesis is to 12 investigate how different organic and conventional management practices under the same crop rotation infl uence tuber quality characteristics as well as yield.Käesoleva doktoritöö raames uuritakse, kuidas erinevad viljelussüsteemid (neli tavaviljeluse süsteemi koos suureneva mineraalse lämmastiku normiga vs kaks mahesüsteemi koos vahekultuuride ja sõnnikuga), mis järgivad sama külvikorda (punane ristik, talinisu, hernes, kartul, oder punase ristiku allakülviga) mõjutavad kartuli kogu ja kaubanduslikke saake, mugulate toiteainete (N, P, K, Ca, Mg), nitraatide (NO3–), tärklise ja kuivaine sisaldust kui ka mugulahaiguste nagu harilik kärn (Streptomyces spp.), hõbekärn (Helminthosporium solani), kuivmädanik (Fusarium spp.) ja märgmädanik (Pectobacterium spp.) esinemist, mida määratletakse ka kui mugulate kvaliteedinäitajaid. Antud töö peamine hüpotees on, et kartuli saagikus ning mugulate toitainete, nitraatide, kuivaine ja tärklise sisaldus kui ka mugulahaiguste esinemine sõltuvad kõik viljelussüsteemist, külvikorrakultuuridest ning kliimatingimustest. Tulenevalt töö hüpoteesist oli uurimustöö eesmärkideks täpsemalt (i) hinnata viljelussüsteemi mõju kartuli saagierinevustele, (ii) uurida, kuidas erinevad viljelussüsteemid mõjutavad mugulate makrotoitainete kontsentratsiooni kui ka kuivaine ja tärklisesisaldust (iii) ning mugulahaiguste esinemist. Uurimistööst ilmnes, et uuritavate aastate keskmisena oli viljelussüsteemidel usutav mõju kartuli saagikusele, mugulate N, NO3–, P ja Mg sisaldustele kui ka mugulahaiguste nagu kuivmädanik, hõbekärn ja harilik kärn (madala nakkustasemega) esinemisele. Seega viljelussüsteemide toitainetega varustatus kui ka nende allikas võivad suuresti mõjutada mõningaid mugulate kvaliteedinäitajaid. Mugulate K, Ca, tärklise ja kuivaine sisaldused kui ka märgmädaniku esinemine vastupidiselt ei olnud mõjutatud erinevatest viljelussüsteemidest ning nende toitainetega varustatusest, kui välistatakse kasvuaasta ilmastikutingimuste mõju. See, kuidas konkreetne süsteem mõjutab mugulate kvaliteediomadusi, on otseselt mõjutatud ka kasvuperioodi keskkonnatingimustest.Publication of this thesis is supported by the Estonian University of Life Science

Kartul mahe- ja tavaviljeluse süsteemide võrdluskatses aastatel 2008-2012

Kartul on üheks armastatumaiks kultuuriks nii meil kui maalimas. Kartulit on läbi aegade peetud teiseks „leivaks“ ning tänapäeval ei kujutaks meist keegi ette oma toidulauda, kui sealt puuduks toidukartul. Maheviljelus on Eestis aasta-aastalt laienenud on mahekartulikasvatuse pindala siiski iga aastaga vähenenud. Uurimistöö eesmärk oli uurida kuidas erinevad viljelusviisid mõjutavad mugulate saagistruktuuri elemente ning kui suurt mõju avaldab see saagi kvaliteedile

Talvine vahekultuur mõjutab kartulimugulate hõbekärnaga nakatumist

Kartuli (Solanum tuberosum L.) hõbekärn (Helminthosporium solani Durieu, Mont) on seenhaigus, mis viimastel aastatel on osutunud tootmises äärmiselt problemaatiliseks. Haigustekitaja nakatab valmivaid mugulaid juba mullas, kuid eoste kaudu levib haigus hoidlas jõudsalt edasi, mistõttu peetakse hõbekärna ka säilitushaiguseks. Patogeen tungib mugulasse läbi loomulike avade siis, kui mugulad on saavutanud juba oma suuruse ja massi, kuid toimub veel koore kinnistumine. Seetõttu on vajalik mugulad põllult võimalikult ruttu koristada. Hõbekärna nakatunud mugulate koore pinnale tekivad pruunikashallid laigud. Kui mugulad puutuvad kokku veega ilmneb nakatunud kohal iseloomulik hõbe-metalne läige. Eriti hästi ongi haigust näha just pestud mugulate pinnalt. Nakatunud mugulatel levivad haiguskolded jõudsalt üle terve mugula ning haigus levib edasi tervetele mugulatele, mis omakorda nakatuvad. Kui hõbekärn on katnud kogu mugula pinna, hakkab selle veesisaldus järk-järgult vähenema. Tekivad massikaod, sest nakatunud mugulad tõmbuvad veekao tõttu kokku. Mugulate hõbekärna nakatumist ei ole võimalik maapealse biomassi järgi tuvastada, sest haigus maapealsel osal ei lööbi. Samuti puuduvad andmed, kui pikalt on hõbekärna tekitaja mullas elujõuvõimeline. Hõbekärna tõrjumiseks puuduvad veel praktilised võtted ning ühtlasi puuduvad ka hõbekärna tekitaja suhtes resistentsed sordid Lebeca jt., mis teeb hõbekärnast kartulikasvatuses ühe ohtlikuma haiguse. Seetõttu ongi vaja uurida, millised agronoomilised võtted on võimelised vähendama mugulate hõbekärnaga nakatumist

In crop rotation green manures as winter cover crops enhance ecosystem services of farming

Organic farming systems should be characterized by excellent soil fertility management to keep plant nutrient cycles short and as closed as possible. Therefore, it is extremely important to establish growing systems that have rotations with appropriate crops and intercrops to ensure fertile and biologically active soils, to enhance biodiversity and to provide high quality crop yields. Locally available organic fertilizers include green manures and animal manure. The influence of green manures as intercrops and these combined with composted cattle manure on soil properties, biodiversity indicators and crop yields was studied in a crop rotation experiment in three organic systems at the Estonian University of Life Sciences

Winter cover crops impact on plant nutrients in an organic crop rotation

In crop rotations winter cover crops (WCC) can play a certain role in organic matter and plant nutrient formation. Under Nordic conditions the selection of crops for winter cover crops is quite limited. The aim of the present research was to explain the biomass and nutrients (N, P and K) formation by certain winter cover crops in an organic crop rotation. The effects of WCC on the following main crop yields were monitored

Viljelussüsteemide mõju mulla süsinikuvarule

Maintaining or enhancing the stock of soil organic carbon (SOC) is a key factor in sustaining the soil resources of the world. The objective of this research was to study the effect of different farming systems (conventional farming with mineral fertilizers vs. organic farming with organic fertilizers (catch crops and composted manure)) under the same 5-crop rotation system on the SOC stock. Data presented in this paper concerned the first rotation during 2008–2012. The main factors were farming systems: conventional and organic. Four conventional farming systems differed in the mineral nitrogen application rates. In two organic farming systems catch crops were used with or without composted solid cattle manure. The SOC stock was determined before experiment and after the first rotation. The stock of SOC increased considerably after the first rotation only in the organic farming systems, where the total C-inputs were higher compared to the C-inputs in conventional systems. The use of mineral N contributed to no change in SOC stock but influenced the quality of soil organic matter. This research revealed that, compared to the other studied systems, in a system in which the highest rate of mineral N was used the more stable C fraction of SOM proportion increased

The long-term trends in soil carbon stock and crop productivity depending on management in Estonia

The dynamics of soil organic carbon (SOC) content and crop productivity were studied on three still continuing field experiments situated at the experimental station of the Estonian University of Life Sciences in Tartu, Estonia. The first trial was established in 1964. The effect of mineral fertilizers and farmyard manure applied to barley and sward with different species composition on soil organic carbon content was studied. The second trial with 3-crop rotation (potato - spring wheat - spring barley) was established in 1989. Experimental factors were organic (without amendment, solid cattle manure and alternative organic fertilisers) and mineral fertilisers (0, 40, 80, 120 and 160 kg N ha-1). The third field experiment with 5-crop rotation experiment was established in 2008. Five different crops were following each other – barley undersown with red clover, red clover, winter wheat, pea and potato. Experimental factors were organic (catch crops as green manures, catch crops as green manures combined with composted cattle manure) and conventional farming systems. The conventional farming systems differed in the amounts of mineral fertilizers used: 0, 50, 100 and 150 kg N ha-1. The first goal of this research was to quantify plant C inputs to the soil in Estonian arable lands and the net primary production using crop-specific allometric relationships. Secondly, the impact of the different management scenarios on the changes in soil C stock was evaluated using plant C input data. The preliminary results of these data analysis will be presented

IMPROVING NITROGEN MANAGEMENT IN REDUCED TILLAGE SYSTEMS BY USE OF GREEN MANURES AND APPROPRIATE OFF-FARM INPUTS: REUSLTS OF TILMAN-ORG. TILMAN-ORG SESSION.

Abstract The TILMAN-project aims to develop robust and sustainable arable crop production systems via the introduction of reduced tillage techniques combined with a strategic use of green manures in organic crop rotations, while maintaining and improving soil quality and crop productivity parameters. The adoption of reduced tillage and/or green manures strongly affects nitrogen quantity and availability during the vegetative period and throughout the crop rotation. Specifically, changing soil and water conditions may affect the availability pattern of nitrogen, notably in spring. We present aggregated data of several long- and medium-term European experimental field studies in which green manures including cut-and-carry-fertilizers, and reduced tillage techniques are used in organic cropping systems. By presenting and analyzing field level nitrogen budgets, insight is gained in the nitrogen dynamics of such systems and possible bottlenecks. Moreover, results of model simulations of these trials by the decision support tool Ndicea are shown and analyzed

Teravilja saak ja saagi kvaliteet sõltuvalt viljelussüsteemist

Jätkusuutlikuks maheviljeluseks on oluline arendada viljelussüsteeme, mis tagaksid elurikkuse suurenemise, mullaviljakuse paranemise ja hea ning kvaliteetse saagi. Selles mängib keskset rolli liblikõielisi kultuure sisaldav ja taimetoitainete tasakaalu säilitav kohalikesse oludesse sobiv külvikord. Taimetoitainetega paremaks varustatuseks saab külvikorras kasutada veel vahekultuure, komposte või sõnnikut. Nende lagunemisel muutuvad toitained taimedele kättesaadavaks aeglasemalt ja ühtlasemalt, kindlustades nii külvikorras järgnevate kultuuride stabiilse varustatuse lämmastikuga. Käesoleva uurimuse eesmärk oli selgitada odra ja nisu saagikus ning saagi kvaliteet nende kasvatamisel viieväljases külvikorras kolmes eri maheviljelussüsteemis, mis erinesid talviste vahekultuuride ja sõnniku kasutamise poolest

Herne saak ja kvaliteet maheviljeluses olenevalt orgaanilise väetamise viisist

Maheviljeluses kasutatakse mitmeaastast külvikorda, mis säilitab ja suurendab mulla viljakust ja bioloogilist aktiivsust ning kus kasvatatakse liblikõielisi ja haljasväetistaimi või kasutatakse väetamisel komposteeritud sõnnikut (Mahepõllumajanduse seadus, 2007; Palts ja Vetemaa, 2012). Seega on õhulämmastikku siduvaid ja mügarbaktereid moodustavate liblikõieliste taimede kasvatamine maheviljeluse üheks põhitingimuseks. Liblikõielised taimede kasvatamine soodustab ka teiste toiteelementide (P, K, mikroelemendid) omastamist mullast või orgaanilisest materjalist. Hernes, kui mahekülvikorda hästi sobiv kultuur on vähenõudlik ja kasvutingimuste suhtes leplik taim, mis kasvab hästi keskmistel liivsavi- ja saviliivmuldadel. Ka ei vaja ta teraks kasvatamisel lämmastikku sisaldavaid väetisi. Sobivaks eelviljaks on hernele teravili. Teraviljad on külvikorras headeks kultuurideks, sest nad aitavad vähendada juuremädaniku probleeme ja ei ole peremeestaimed teiste kultuurirühmade, sh herne juuremädaniku patogeenidele või nematoodidele (Abawi jt., 2014). Uurimuse eesmärgiks oli selgitada erinevate orgaaniliste väetusviiside mõju herne saagile ja kvaliteedile maheviljeluses