Cover cropping has a potential to improve soil health in semiarid regions. This research evaluated the effects of spring-planted cover crops on selected soil health indicators in limited-irrigated winter wheat (Triticum aestivum L.)-fallow system. Soil health parameters measured include soil water content (SWC), soil organic carbon (SOC), soil total nitrogen (STN), potentially mineralizable carbon (PMC), potentially mineralizable nitrogen (PMN), permanganate oxidizable carbon (POXC), inorganic N, and available P. Cover crops tested were pea (Pisum sativum L.), oat (Avena sativa L.), canola (Brassica napus L.), pea + oat (PO), pea + canola (PC), pea + oat + canola (POC), pea + oat + canola + hairy vetch (Vicia villosa L.) + forage radish (Raphanus sativus L.) + barley (Hordeum vulgare L.) (SSM), and a fallow. Cover crops were planted in February and terminated in May after 85 to 90 d. Cover crop biomass was 33 to 142% greater with oat, PO, PC, POC, and SSM than pea and canola. The SWC was 2 to 3% lower under cover crops than fallow plots at their termination, but was 2 and 4% greater in SSM and POC than fallow at wheat planting in October. Soil inorganic N was 41 to 49% lower with cover crops than fallow at termination date. Soil PMC and POXC varied with cover crop species and sampling dates. The SOC and STN contents were 18 to 20% greater with oat than PC. Oat and its mixture with other cover crops show promises to improve soil health and resilience.

Decline in soil organic carbon (SOC) and the associated impacts on crop production under conventional farming raises concerns on how alternative management practices increase SOC sequestration and improve agricultural sustainability. This study aimed to understand SOC mineralization kinetics with different cover crop (CC) residue amendments. Soil samples were collected from a fallow and three CC (pea, oat, and canola) plots. Soil samples from the CC plots were manipulated with zero, five, and 10 Mg ha −1 of the respective CC residues. All soil samples were incubated for eight weeks, SOC mineralization was monitored, and the first order kinetic and parabolic equation models were fitted to the observed data for estimating labile SOC (C 0 ), and the decomposition rate constant (k). Subsequent comparisons of fitted model parameters were based on the first order kinetic model. The C 0 varied with the residue amount while k varied with CC type. C 0 was 591-858% greater with 10 Mg ha −1 and 289-456% greater with five Mg ha −1 residue additions while k was 122-297% greater with 10 Mg ha −1 and 94-240% greater with five Mg ha −1 residue additions when compared to the fallow treatment. The CC residue stimulated cumulative carbon mineralization (C min ) irrespective of CC type, suggesting that cover cropping has potential to improve SOC cycling in agroecosystems.

A 3-yr study was conducted in eastern Wyoming from 1995 to 1997 to evaluate the effect of fertilizer placement on jointed goatgrass competitiveness with winter wheat. Fertilizer placement methods consisted of applying 45 kg/ha of nitrogen (50% as urea and 50% as ammonium nitrate) in a deep band 5 cm below and 2.5 cm to the side of the wheat row, broadcasting on the soil surface, or injecting fertilizer by spoke wheel 10 cm deep and 5 cm to the side of the wheat row. Neither fertilizer placement nor jointed goatgrass presence affected winter wheat stand. Wheat yield reductions from jointed goatgrass competition were 7 and 10% higher with the broadcast than deep-band or spoke-wheel injection methods, respectively. Wheat spikes/plant, seeds/spike, 200-seed weight, and plant height were not influenced by fertilizer placement; however, the presence of 35 jointed goatgrass plants/m2reduced spikes/plant 21%, seeds/spike 12%, and 200-seed weight 6%. Jointed goatgrass populations were not influenced by fertilizer placement method; however, the number of spikes/plant was reduced 8 and 10%, joints/spike 3%, and biomass 15 and 21% by deep band or spoke wheel fertilizer placement.

Core Ideas Canola forage production was higher than wheat in fall but not in later harvests. Many of the forage quality parameters were superior in canola compared with wheat. Forage harvest decreased canola yield even before bolting but not in wheat. Canola has dual‐purpose use potential (forage and seed yield) with LF harvest. Winter canola (Brassica napus L. biennus) has the potential to be a dual‐purpose crop in the US Southern Great Plains, a region with cereal fallow mono‐cropping. However, there is little information on dual‐purpose canola in the region. Therefore, field studies were conducted in Clovis, NM, in 2013, 2014, and 2015 to compare harvesting time effect on forage productivity (dry matter), quality, and oil and seed production of canola and wheat. Harvesting time treatments were late‐fall (LF), mid‐winter (MW), early‐spring (ES), late‐spring (LS), and no‐harvest (NH). The two forage crops were canola (cv. DKW44‐10, Griffin, and Safran) and wheat (cv. TAM 111 and TAM 113). In general, crop dry matter increased and forage nutritive values decreased with delay in harvest. Dry matter of LF to ES harvests ranged from 2950 to 7740 (canola) and from 2390 to 7490 kg ha−1 (wheat), suggesting superior forage production of canola with LF to ES harvests. Crops had similar crude protein and acid detergent fiber. Canola's neutral detergent fiber was lower (238 vs. 425 g kg−1), whereas its relative feed value (188–425) was higher than wheat (127–204). Average canola seed yields (excluding 2014) were 4360, 3040, 2940, and 2720, 930 kg ha−1 with the NH, LF, MW, ES, and LS forage harvests, respectively. Forage harvest had inconsistent effects on wheat seed yield. These results show canola's potential to produce high‐quality forage and seed yield and indicate that canola can be used as a rotational break crop in the crop–livestock production systems of the Southern Great Plains.

Two furrow irrigated field experiments were conducted for two years at the Research and Extension Center, Powell, WY to determine the influence of various mixed densities and durations of wild oat and wild mustard interference in sugarbeet. Sugarbeet root yields were reduced by competition from all examined densities of wild oat and wild mustard, alone and in combination. Root yield reduction was less than additive with mixed densities of wild oat and wild mustard. Root yields decreased as the duration of interference after sugarbeet emergence from a mixed density of wild oat and wild mustard increased. Sucrose content of sugarbeet was not altered by competition. Based on regression analysis, the minimum time that a mixed density of 0.8 wild mustard and 1 wild oat/m of row can interfere with sugarbeet before causing an economic root yield loss was approximately 1.6 weeks after sugarbeet emergence.