Crop rotations for grain production

There is an increasing demand for organically grown cereal grains in Denmark, which is expected to cause a change in the typical organic farm structure away from dairy farming and towards arable farming. Such a change may reduce the stability of the farming systems, because of decreasing soil fertility and problems with weed control. There have only been a limited number of studies under temperate conditions in Europe and North America, where different crop rotations have been compared under organic farming or similar production conditions

Crop production during the first course of an organic crop rotation trial in Denmark

Three factors are included in a factorial field experiment: 1) fraction of grass-clover and pulses in the rotation (crop rotation), 2) catch crop (with or without catch crop), and 3) manure (with or without animal manure). Manure is applied as slurry in rates corresponding to 40 % of the nitrogen demand. Grain yields for three sites and three years of the experiment are presented for two four-course rotations. One rotation has a green-manure crop, which is replaced by winter wheat in the other rotation. The use of manure significantly increased grain yield of the cereal crops in most cases. The positive effects of the catch crops were mainly observed in the spring cereals. The largest rotation yields were obtained in the crop rotation without a green manure crop. The positive effect of a green manure crop could not substitute for the yield decrease from leaving 25% of the area out of produc-tio

Design of an organic farming crop rotation experiment

A field experiment is conducted which focuses on crop rotations for cereal production in organic farming. The objective of the experiment is to explore the possibilities for both short-term and long-term increases in organic cereal production through manipulation of crop rotation design on different soil types. This paper describes the design of a rather complex experiment, and later papers will describe and discuss the results. Three factors are included in the experiment in a factorial design with two replicates: A) fraction of grass-clover and pulses in the rotation (crop rotation), B) catch crop (with or without catch crop or bi-cropped clover), and C) manure (with or without animal manure applied as slurry). All fields in all rotations are represented each year. The experimental factors are defined to allow management to be adjusted for optimisation of the individual treatment combinations. This makes the systems more realistic and the results more applicable in practical farming. The experiment is conducted at four locations representing major soil types and climate regions in Denmark. The main design criteria are related to requirements for a long-term experiment and the need of performing studies and experiments within the experiment itself

Whole-rotation dry matter and nitrogen grain yields from the first course of an organic farming crop rotation experiment

The possibilities for increasing total grain yield in organic cereal production through manipulation of crop rotation design were investigated in a field experiment on different soil types in Denmark from 1997 to 2000. Three experimental factors were included in the experiment in a factorial design: 1) proportion of grass-clover and pulses in the rotation, 2) catch crop (with and without), and 3) manure (with and without). Three four-course rotations were compared. Two of the rotations had one year of grass-clover as a green manure crop, either followed by spring wheat or by winter wheat. The grass-clover was replaced by winter cereals in the third rotation. Animal manure was applied as slurry in rates corresponding to 40% of the nitrogen (N) demand of the cereal crops. Rotational grain yields of the cereal and pulse crops were calculated by summing yields for each plot over the four years in the rotation. The rotational yields were affected by all experimental factors (rotation, manure and catch crop). However, the largest effects on both dry matter and N yields were caused by differences between sites caused by differences in soils, climate and cropping history. The rotation without a green manure crop produced the greatest total yield. Dry matter and N yields in this rotation were about 10% higher than in the rotation with a grass-clover ley in one year of four. Therefore, the yield benefits from the grass-clover ley could not compensate for the yield reduction as a result of leaving 25% of the rotation out of production. There were no differences in dry matter and N yields in grains between the rotations, where either spring or winter cereals followed the grass-clover ley. The N use efficiency for ammonium-N in the applied manure corresponded to that obtained from N in commercial fertilizer. There were only very small yield benefits from the use of catch crops. However, this may change over time as fertility builds up in the system with catch crops

Udbytter i sædskifter til økologisk kornproduktion

Ved Danmarks JordbrugsForskning blev fire forskellige sædskifter med forskellige andele af korn afprøvet i årene 1997-2000. Udbytterne varierede betydeligt mellem forsøgsstederne og afhang desuden af sædskifte, gødning og efterafgrøde. Forsøget fortsætter med nogen justering i en ny 4-års rotation

Lokalitetens og dyrkningsvilkårenes betydning i økologisk planteavl

Der er store forskelle mellem lokaliteter med hensyn til udbytteniveau, udvaskning af næringsstoffer og forekomst af ukrudt. Mens de største kornudbytter blev høstet på lerjordene blev den største mængde råprotein i ært/byg høstet på sandjordene. Udvaskningen af N var størst på den grovsandede jord. Fangafgrøder havde størst effekt på udvaskningen på Jyndevad og ingen effekt på Flakkebjerg. Allerede i løbet af den første 4-årige rotation ændrede dyrkningsbetingelserne sig meget. Kløvergræs øgede frugtbarheden betydeligt på Flakkebjerg. Kvik er blevet et stort problem på Jyndevad og tidsler forekommer udbredt på Flakkebjerg og Holeby

Danske forskere tester sædskifter

Siden 1997 har fire forskellige sædskifter med forskellige andele af korn været afprøvet. Udbytter og kvælstofudvaskning varierer mellem forsøgsstederne og er afhængig af sædskifte, efterafgrøde og gødning

Økologisk vinterhvede kan lykkes på god jord

På planteavlsbrug er mulighederne for indkøb af husdyrgødning ofte begrænset til indkøb af konventionel husdyrgødning inden for grænsen på 25% af kvælstofbehovet. Muligheder for at tilgodese afgrødernes næringsstofbehov på denne måde afhænger af bortførsel af næringsstoffer med afgrøderne og hvor store især udvaskningstabene er. Andre metoder til at tilgodese afgrødernes behov for kvælstof må derfor udnyttes optimalt, herunder anvendelse af grøngødningsmarker

Udbytter i forsøgssædskifter til kornproduktion

For at belyse mulighederne for at dyrke mere økologisk korn til modenhed, blev der i 1996/97 anlagt et økologisk sædskifteforsøg på fire lokaliteter i Danmark: · Jyndevad (JB1) i Sønderjylland, · Foulum (JB4) i Midtjylland · Flakkebjerg (JB6) på Sjælland · Holeby (JB7) på Lolland Sædskifterne repræsenterer systemer med forskellige andele af korn og kvælstoffikserende afgrøder. De har været afprøvet med fire forskellige kombinationer af fangafgrøder (uden og med) og husdyrgødning (uden og med). Det giver en bred vifte af informationer om de enkelte systemers produktionsevne og stabilitet

Sædskiftets indre dynamik i økologisk planteavl

Jordens frugtbarhed opbygges og vedligeholdes gennem anvendelse af grøngødning, efterafgrøder og bælgsæd. I et forsøg med økologiske kornsædskifter var der på lerjorden og den lerblandede sandjord en god sammenhæng mellem udbyttet i vinterhvede og kvælstofopsamlingen i den forudgående kløvergræs, hvorimod kvælstofudvaskning på den grovsandede jord reducerede udbyttet i vinterhvede betydeligt. Lupin var en betydelig bedre forfrugt til korn end ært:byg, og på trods af meget lavere udbytter i lupin, var proteinudbyttet på sædskifteniveau det samme i sædskifter med lupin som med ært:byg. Der var både positive og negative effekter af fangafgrøder, men på det samlede udbytte i sædskiftet gav fangafgrøder en udbyttestigning på 1,1 til 2,4 hkg/ha/år. Husdyrgødning øgede udbyttet i kornafgrøderne, men kan også bremse etableringen af især kløverudlæg, og anvendelse af husdyrgødning bør derfor indpasses rigtigt i sædskiftet