Search

Nitrogen supply, environment, and cultivar determine yield and dough properties of hard red spring wheat (Triticum aestivum L.); however, the effects of broadcasting N fertilizer at heading, a growing practice in regions such as southern Brazil, have not been explored. The objectives of this study were to: (i) compare the current producer practice vs. alternative fertilizer N management strategies and (ii) quantify their interaction with cultivar and their effects on yield and its components and relevant dough properties. Field experiments were conducted using a complete factorial arrangement in a split-plot design of three cultivars (main plots) and five N strategies (subplots) across three environments in southern Brazil. Overall, the current producer practice (all 70 kg N ha-1 applied at tillering) was appropriate to the targeted yield (3.5 Mg ha-1); splitting this fertilizer N rate into tillering and heading applications (either 35 kg N ha-1 on tillering + 35 kg N ha-1 on heading or 45 kg N ha-1 on tillering + 25 kg N ha-1 on heading) benefited protein concentration but reduced yield. Best N management resulted in the addition of one late-season N application (70 kg N ha-1 on tillering + 23 kg N ha-1 on heading) positively impacting yield, protein concentration, dough extensibility, and alveogram index. In-season N management is more relevant for grain quality than yield, more importantly if deductions from low protein are projected, or if premiums from increasing protein concentration exist, justifying a late-season fertilizer N application. [ABSTRACT FROM AUTHOR]

Uniform within-row plant spacing is a key crop management strategy to achieve high corn (Zea mays L.) yield. A new precision planting concept is emerging based on the use of modern devices in planters. The objective of this study was to investigate the impact of optimizing within-row plant spacing to enhance plant nutritional status and corn yield. The treatments investigated were (a) traditional planter with mechanical horizontal plate metering system (TP), (b) precision planter with vSet (Precision Planting, Tremont, IL) vacuum meter system (PP) and (c) PP pulled by a tractor equipped with an real time kinematic (RTK)-based auto-steering system (APP). The experimental design was a randomized block with three replications, and the plant evaluations were determined based on a main plot and a plant-to-plant study. Two types of vegetation indexes (VI and normalized diff erence, NDVI) were used for assessing plant nutritional status. A high standard of uniform plant spacing (CV < 10%) was required to achieve the highest corn yield. Optimizing the within-row plant spacing resulted in higher VI and NDVI. Based on the average of two experiments, PP improved the uniformity of plant spacing (CV = 22.5%) compared to TP (CV = 38.7%). This optimization of within-row plant spacing increased the corn yield by 10.7%. Only in the year with higher corn yield potential did APP result in a yield increase of 6.9% in relation to PP. Although the precision planters investigated had decreased the error in plant distribution, no one reached the plant spacing uniformity required to achieve higher corn yields. [ABSTRACT FROM AUTHOR]

Cover crops (CC), particularly legumes, are key to promote soil carbon (C) sequestration in no-tillage. Nevertheless, the mechanisms regulating this process need further elucidation within a broad comprehensive framework. Therefore, we investigated effects of CC quality: black oat (Avena strigosa Schreb) (oat), common vetch (Vicia sativa L.) (vetch), and oat + vetch on carbon dioxide-C (CO2-C) emission (124 days) under conventional- (CT), minimum- (MT) and no-tillage (NT) plots from a long-term experiment in Southern Brazil. Half-life time (t1/2) of CC residues and the apparent C balance (ACB) were obtained for CT and NT. We linked our data to long-term (22 years) soil C and nitrogen (N) stocks and crop yield data of our experimental field. Compared to CT, NT increased t1/2 of oat, oat + vetch and vetch by 3.9-, 3.1- and 3-fold, respectively; reduced CO2-C emissions in oat, oat + vetch and vetch by 500, 600 and 642 kg ha−1, respectively; and increased the ACB (influx) in oat + vetch (195%) and vetch (207%). For vetch, CO2-C emission in MT was 77% greater than NT. Legume CC should be preferentially combined with NT to reduce CO2-C emissions and avoid a flush of N into the soil. The legume based-NT system showed the greatest soil C and N sequestration rates, which were significantly and positively related to soybean (Glycine max (L.) Merrill) and maize (Zea mays L.) yield. Soil C (0–90 cm depth) and N (0–100 cm depth) sequestration increments of 1 kg ha−1 corresponded to soybean yield increments of 1.2 and 7.4 kg ha−1, respectively. [ABSTRACT FROM AUTHOR]