Yield, Quality, and Water and Nitrogen Use of Durum and Annual Forages in Two‐Year Rotations

Abstract

All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. C rop diversification, reduced fallow periods, and limited inputs are being promoted in the Great Plains to improve economic and environmental sustainability in dryland cropping systems (Peterson et al., 1993). In Montana, more than 1.59 million ha or 36% of the dryland acreage for annual crop production was in summer fallow in 2003 (NASS, 2010). Producers are encouraged to diversify crops away from monocultures, primarily wheat (T. aestivum L.), to reduce the area of land under fallow, and to reduce farm inputs, especially those that have negative impacts on economic and environmental sustainability (Matson et al., 1997; Struick and Bonciarelli, 1997; Gregory et al., 2002). Water typically is the primary limiting factor for growing crops in durum-based cropping systems in the semiarid northern Great Plains (NGP). Conventional summer fallow usually increases both soil water storage and NO 3-N concentration for subsequent crop use. Summer fallow, however, is ineffi cient for precipitation storage, averaging only 25% effi ciency in tilled systems (Farahani et al., 1998). Intensifi cation of crop production by reducing summer fallow provides more effi cient utilization of water in the semiarid central Great Plains (Farahani et al., 1998). Available N is the second most limiting factor for dryland crop production in semiarid agroecosystems (O'Leary and Connor, 1997). Soil NO 3-N availability is usually related to cereal yields. Increased NO 3-N content can also contaminate surface and groundwater due to N leaching and surface runoff. For decreasing fertilizer N applications and improving N utilization, producers are encouraged to diversify away from cereal monocultures, primarily spring wheat and durum, to improve crop N uptake and reduce residual soil N and N leaching. Additionally, purchasing fertilizer N is a signifi cant expense for producers. Improved nutrient-use effi ciency, particularly N, is an important goal in cropping systems (Karlen et al., 1994; Raun and Johnson, 1999). Huggins and Pan (2003) showed determination of key indicators of nitrogen use effi ciency (NUE) in cereal-based agroecosystems enabled broad assessment of agronomic management and environmental factors related to N use. Key indicators of NUE include N in grain and N aboveground biomass, N harvest index, and grain N accumulation effi ciency. Annual cereal forage crops are well adapted to semiarid NGP

The importance of reduced meat and dairy consumption for meeting stringent climate change targets

“…Regional estimates of N efficiencies range from 28 % for rice in China (Fan et al 2009) to about 75 % in forages (Smil 2001;Lenssen et al 2010). We use data from Cassman et al (2002), Ladha et al (2005), and Smil (2001) to estimate current N efficiencies for different crops in Europe.…”

Review: Redesigning Canadian prairie cropping systems for profitability, sustainability, and resilience

“…(1 and can provide mid-to late-season grazing, either as a standing crop or in swath McCartney et al 2008McCartney et al , 2009Lenssen et al 2010). Mixtures of annual cereals and legumes can produce large amounts of high-quality forage biomass (Carr et al 1998(Carr et al , 2004Strydhorst et al 2008).…”

Net Greenhouse Gas Emissions Affected by Sheep Grazing in Dryland Cropping Systems

“…Pea/barley hay uses less soil water than durum because of early harvest, and the absence of plants during fallow increases soil water content (Lenssen et al, 2010). Although sheep grazing is effective in controlling weeds, it may not be as effective as herbicide application because some weeds and plants may survive for a longer period (Hatfield et al, 2007).…”