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The nutritive quality of four cultivars of canola forage (Brassica napus L.), Orient, Midas, Global, and Hybrid (Cobra × Regent), which were harvested in the early-spring period, were compared with green-winter barley (GWB) in terms of their yields, chemical composition, in vitro gas production variables, in situ crude protein (CP) degradation, and predicted dry matter intake (PDMI). Data were statistically analyzed using a completely randomized design with four replications and three samples per replication. The study was based on a randomized complete block design, and data were analyzed using SAS, general linear model procedure for normal distribution. The canola dry matter (DM) yield was highest in Orient cultivar and lowest in Midas (P < 0.05). Organic matter (OM), CP, neutral detergent fiber (NDF), and lignin(sa) concentration of the four cultivars ranged from 862 to 865, 218 to 247, 295 to 340, and 35 to 53 g/kg DM, respectively. The estimated OM disappearance (OMD), effective degradability of CP, effective rumen degradable protein (ERDP), digestible undegradable protein, and metabolizable protein (MP) of the forages were from 636 to 671 g/kg, 878 to 910, 172 to 193, 1.9 to 3.4, and 112 to 126 g/kg DM, respectively. Compared to Global and Hybrid cultivars, Orient and Midas contained higher CP, OMD, ERDP, MP concentration, and PDMI, but lower NDF, acid detergent fiber (ADF), and lignin(sa) concentrations (P < 0.05). The level of glucosinolates in the forages ranged from 0.38 to 1.51 µmol/g DM, which is below the detrimental level for ruminants. Compared to winter canola cultivars, GWB had higher DM yield (P < 0.003), NDF, lignin(sa), PDMI (P < 0.01), and digestible undegradable protein (P < 0.04), but had lower OMD (P < 0.03), ERDP (P = 0.01), and MP (P < 0.009). Based on the obtained results, the variation in the nutritive quality among the canola cultivars is relatively small, and the Orient cultivar, which is most comparable to GWB, was judged to be nutritionally the best among the cultivars. [ABSTRACT FROM AUTHOR]

With regard to the low cation-exchange capacity and large saturated hydraulic conductivity of sandy soils, a field experiment was carried out in 2006–2007 to determine the impact of zeolite on nitrogen leaching and canola production. Four nitrogen (N) rates (0, 90, 180, and 270 kg ha–1) and three zeolite amounts (3, 6 and 9 t ha−1) were included as treatments. The results demonstrated that the highest growth parameters and seed yield were attained with 270 kg N ha−1 and 9 t zeolite ha−1. However, the highest and the lowest seed protein percentage and oil content were obtained with 270 kg N ha−1 accompanied by 9 t zeolite ha−1, respectively. Nitrate concentration in drained water was affected by nitrogen and zeolite. The lowest and highest leached nitrate values were found in control without N and zeolite (N0Z0) and in treatments with the highest N supply without zeolite (N270Z0), respectively. In general, nitrogen-use efficiency decreased with an increase in N supply. Application of 9 t zeolite ha−1 showed higher nitrogen use efficiency than other zeolite amounts. Also, application of more N fertilizer in soil reduced nitrogen uptake efficiency. In total, application of 270 kg N ha−1 and 9 t zeolite ha−1 could be suggested as superior treatment. [ABSTRACT FROM AUTHOR]

Selection of an appropriate forage species is an important first step in successful forage production. Among forage species, canola (Brassica napus L.) can be cut for hay or silage to cover certain costs of growing the crop. Because forage production is largely controlled by the environment and management, this experiment was conducted in a semiarid region of Iran during the 2006-2007 and 2008-2009 growing seasons to investigate whether canola forage yield and its nutritive value affected by different rates of N and natural zeolite. The experimental treatments were arranged in randomized complete blocks with three replications and comprised a factorial combination of three N levels (90,180, and 270 kg N ha-1) and four zeolite rates (0,3,6, and 91 zeolite ha-1 ). The results showed that the enhanced N application from 90 to 270 kg N ha-1 resulted in a 49% rise in forage yield for the first year and a 39% increase for the second year. The converse effects from N and zeolite yielded a significant interaction on the forage nitrogen concentration (FNC) so that the N and zeolite application enhancement led to an increase and decrease, respectively, in the FNC. The integration of the minimum N level with the maximum zeolite application generated the highest forage calcium concentration (FCC) (1.13% in dry matter). In contrast, N270Z0 treatment yielded the lowest FCC (0.54% in dry matter). There was a linear response between N application rate and its leaching loss whereas in the zeolite treatments, minimum N leaching was observed after the Z9 treatment. A combined application of zeolite and chemical N for canola production in a poor sandy soil is recommended to ensure an acceptable forage yield and for soil protection from excess N leaching loss. [ABSTRACT FROM AUTHOR]

A field experiment was carried out in a semi-arid region of Iran during the 2006–2007 growing season to investigate canola seed yield as affected by nitrogen (N) and natural zeolite (Z) rates. This experiment studied N efficiency and N leaching loss in a sandy soil. Experimental treatments consisted of a factorial combination of three N levels (90, 180, and 270 kg N ha−1) and four zeolite rates (0, 3, 6, and 9 t zeolite ha−1). The result showed that the greatest seed yield (2452.3 kg ha−1) was obtained from the N270Z9 treatment whereas the control treatment (N0Z0) produced the lowest seed yield (1038.3 kg ha−1). Moreover, use of 270 kg N ha−1 without zeolite (N270Z0) led to the greatest amount of N leaching loss (144.23 kg ha−1). Zeolite application clearly reduced N leaching loss in all N rates. This justified low N-use efficiency in high N applications. More N uptake and more canola seed yield is attributed to zeolite application. [ABSTRACT FROM AUTHOR]