Crop Yield Sample Clauses

Crop Yield. Brussels sprouts yields for the North and South plots were sampled at the time of harvest in each year of the field trial (See Table 5 for the sampling dates.) At each sampling, two types of yield data were recorded for each subplot within the North and Crop yield sampling in North plot (11/7/12). Top: View of the North plot just prior to sampling. Bottom: Harvesting the fruit from the sampled stalks into the buckets South plots to inform biomass and crop yield. To measure biomass the stalk with fruit attached was cut at the base and then weighed using a hanging scale. Twenty one stalks were harvested randomly from each subplot and weighed. To measure crop yield, all fruit from the 21 sampled stalks were then harvested and placed in 5-gallon buckets and weighed. Within the test plots, harvesting of plants was done by hand, while a mechanical harvester was used for the rest of the North and South fields.

Crop Yield. The Brussels sprout fruit yield and biomass sampling data were analyzed to determine if significant gains or losses resulted from the treatments over time and when compared with the control. Fruit weights were summed for each subplot within the North and South plots. For each treatment within the North and South plots, the total fruit weight by treatment (i.e. the sum of the four replicate subplot yields) was calculated. For each treatment within a plot (North or South) average fruit weight per subplot and average stalk with fruit weight in each subplot were also calculated. Standard errors for these averages were calculated for each treatment following the recommend method in “A Guide to Conducting Biochar Trials” by the International Biochar Initiative (Major 2009), and then the data was analyzed with respect to differences between treatments and the control, between North and South plots, and over time. Due to the different varieties of Brussels sprouts grown in the North and South plots, yield data from the plots were not combined in the analysis results and discussion. Crop yield results from the subplot samplings were also scaled to per-acre yields based on an assumption of 14,500 plants per acre for Confidant (North plot), and 11,500 plants per acre for Cobus (South plot).

Crop Yield. Results from the three-year field trial suggest that the biochar-only and biochar-compost mix soil amendments had neutral or negative effects on crop yields for conventionally-grown Brussel sprouts in coastal San Mateo County. The compost-only treatment had a neutral or positive affect on crop yields. A variety of factors are discussed here to identify potential causes of these outcomes. A meta-analysis by Xxxxxxx et al (2011) of biochar effects on the yields of other row crops from both field and lab studies, suggests a few mechanisms that lead to the greatest positive effects on crop yield. Biochar can increase soil pH which has been identified as potential cause for crop yield increases in acidic soils. Maintaining a soil pH greater than 6.5 is important for Brussels sprouts growth in this location. But in the field trial, the pre-planting lime application likely precluded this benefit of the biochar-containing soil amendments. Biochar particles are negatively charged and can improve nutrient retention and availability in soils with low CEC. However, the field trial soils had sufficient CEC levels, and this specific benefit of biochar was unlikely for this location. Improved water holding capacity is another potential mechanism for increased crop yields due to biochar use. Water holding capacity is a function of the soil texture and SOM content. Soils in the field trial were loams (North plot to 24”, South to 6”) and clay loams (North >24” and South >6”) which have a relatively high water holding capacity. SOM increases during the field trial could have further improved water holding capacity. However, SOM did not increase in the North plot as a result of the biochar-only and mix soil amendments, and may have declined in soils treated with only compost. The South plot had significantly higher SOM levels resulting from the treatments which may help explain why crop yields in the biochar-only and mix-treated soils – were relatively improved compared with the same set of results in the North plot. (See 5.b Soil Health for further discussion of the SOM results.) Another consideration is that the application of the (raw) biochar-only treatment could have initially resulted in a decrease in bioavailability of nutrients in the soil. Due to it’s negatively charged particles, biochar binds well to positively charged nutrients (e.g., Ca, Mg, K, Na, and ammonium-N). Over time, this effect can enable biochar to act as a slow-release fertilizer, but initially it can...