Part of experiment rbk1

Broadbalk Yields - Other Crops and Fallow

Broadbalk Description of other crop yield data
Other arable crops and fallow have been included in the rotational sections of Broadbalk since 1968 (see Cropping plan for details). See below for further details of fertilizer applications and other treatments, including to the fallow sections . Yield data is available from the following datasets:

BKBEANS Spring bean grain and straw yields 1968 -1978; Winter bean grain and straw yields 2018 -
BKPOTATO Potato tuber yields 1968 -1996
BKMAIZE Forage maize whole crop yields 1997 - 2017
BKOATS Winter oat grain and straw yields 1996 - current year

Spring field beans (Vicia faba) were grown on the rotational sections of Broadbalk between 1968 and 1978, as part of the potato > beans > wheat rotation on sections 2, 4 and 7. For full details of the cropping sequence see Cropping on Broadbalk. The varieties were Maris Bead (1968-74), Minor (1975) and Minden (1976-78). The beans were sown in March and generally harvested in September. The crops received the same inorganic fertilizer (including N) and FYM applications as the wheat crops. The N is applied in the seedbed. Grain and straw yields at 85% DM, thousand grain weights, variety, sowing and harvest dates are available from dataset BKBEANS.

Winter field beans (Vicia faba) replaced forage maize on the rotational sections of Broadbalk from 2018 onwards, and the rotation was changed to wheat/wheat/oats/wheat/beans. For full details of the cropping sequence see Cropping on Broadbalk. The beans are sown in the autumn and harvested in August/September. No fertilizer N or FYM is applied; P, K and Mg are as for the wheat crops. Grain and straw yields at 85% DM and thousand grain weights are available, along with variety, sowing and harvest dates from dataset BKBEANS.

Potato (Solanum tuberosum) was grown on the rotational sections of Broadbalk between 1968 and 1996, as part of the potato > beans > wheat rotation of Sections 2, 4 and 7 (1968-78) and then as part of the potato > wheat > wheat > wheat > fallow rotation of Sections 2-5 and 7 (1979-96). For full details of the cropping sequence see Cropping on Broadbalk. The varieties grown were Majestic (1968-69), King Edward (1970-75), Pentland Crown (1976-93), Estima (1994-96). The crops received the same inorganic fertilizer and FYM applications as the wheat crops. Fertilizer N was applied in the spring, before rotary cultivation to prepare the seedbed. Chitted potato seed was generally planted in April and harvested in September; please apply to the e-RA Curators for a full list of dates since 1968. The potatoes were usually harvested earlier than normal to allow timely drilling of winter wheat, hence the yields are lower than might be expected.

Data available includes total tuber yield, tuber DM content and % ware (tubers that do not pass through a 3.81cm ‘riddle’ or grader). ‘Ware’ potatoes are those grown for human consumption, which need to be a minimum size, generally over 40mm. Potatoes are graded according to size, using a potato riddler.

Forage maize (Zea mays) was grown as a whole crop, for silage. It has been grown in the rotational sections 2-5 and 7, 1997-2017, as part of the wheat > wheat > wheat > oats > maize rotation. Maize is a C4 plant. As such, the carbon it contains has a different ¹³C "signature" than that in the C3 plants that have been grown previously on Broadbalk. Thus, we can distinguish maize-derived organic matter from that of organic matter already in the soil. For full details of the cropping sequence see Cropping on Broadbalk. The variety Hudson was grown 1997-2014, and the variety Severus 2015-2017. Forage maize is generally sown in May and harvested in September; please apply to the e-RA Curators for a full list of dates since 1997. Maize receives the usual inorganic fertilizer and FYM applications, the same as wheat. In 2013, forage maize yields may have been reduced, due to the accidental application of herbicide to the crop in June/July 2013. The last crop of forage maize was grown in 2017. A new rotation including winter beans instead of maize was started in 2018.

Winter oats (Avena sativa) has been grown on the rotational sections 2-5 and 7 since 1996, as part of the wheat/wheat/wheat/oats/maize rotation. For full details of the cropping sequence see Cropping on Broadbalk. The varieties grown were Image (1996-2000), Revisor (2001) and Gerald (2002-onwards). Revisor, a spring variety, was sown in 2001 due to poor autumn weather preventing a winter variety from being sown. Oats are generally sown in October and harvested in August; please apply to the e-RA Curators for a full list of dates since 1996. No fertilizer N or FYM was applied to the oats crops harvested 1996-2017; K and Mg were applied as usual. Thus, on plots were P and K is not limiting, any differences in yield between treatments were due to residues of inorganic N from previous applications or from differing amounts of N being mineralised from the soil organic matter.

Since 2018 the rotation was changed to wheat/wheat/oats/wheat/beans, and N is now applied to the oats at 1/2 the usual rate as a single application in mid-April (i.e. 24, 48, 72, 96, 120 and 144 kgN/ha). FYM is applied at the usual rate to the sections growing oats.

Bare fallow, 1968-1995 was included as part of the three year rotation (wheat > wheat > fallow) on sections 3, 5 and 6 from 1968-1979, and as part of the three or five year rotation on sections 2-5 and 7 from 1979-1995. The fallow sections received FYM and castor meal, and the autumn inorganic fertilizers (P, K, Na and Mg) at the same time as the cropped sections (in the autumn, before ploughing). However, no inorganic N was applied to the fallow sections. The fallow sections were cultivated several times, to remove weeds, and herbicides were also applied. The continous wheat sections (0, 1, 6, 8 and 9) are occasionally bare fallowed to control perennial weeds, most commonly Section 8 (which does not receive herbicides).

Bare fallow, 1926-1967. Regular bare fallowing was introduced in 1926, with cultivations to kill the weeds. No FYM, castor bean meal or inorganic fertilizer was applied to the fallow sections. This decreased the soil organic matter content, especially on the plots usually given FYM. No herbicides were applied to the fallow sections.

For more information, refer to the Rothamsted Guide to the Classical Experiments 2018 pages 7-12.