A current estimate of global phosphorus use effi ciency (PUE) for cereal production is not available. Th e objectives of this paper were to estimate PUE for cereal crops grown in the world and to review methods for improvement. Phosphorus use effi ciency was determined using world cereal harvested area, total grain production, and P fertilizer consumption from 1961 to 2013, in addition to assumptions established from previous literature. World PUE of cereal crops was calculated using both balance and diff erence methods. Using the balance method, cereal grain P uptake is divided by the P fertilizer applied. Alternatively, the diff erence method accounts for P coming from the soil and that is subtracted from applied P. Utilized in this analysis is the estimate that cereal production accounts for 61% of the total harvested cropland. Cereal grain yields increased from 1.35 to 3.90 Mg h -1 between 1961 and 2013. In 1961, the world's fertilizer P consumption was 4,770,182 Mg and increased to 16,662,470 Mg of P fertilizer by 2013. Th is represents a 3.5× increase in P fertilizer consumption over 53 yr. Phosphorus use effi ciency estimated using the balance method was 77%. Using the diff erence method, PUE for cereal production in the world was estimated to be 16%.

Methods that estimate the probability of agricultural drought using atmospheric data can be widely applied but have not been compared with actual drought occurrence indicated by soil moisture measurements. Our objectives were to develop a drought probability assessment method using long‐term measurements of soil water deficits (SWDs) and to compare the resulting probabilities with those of an existing method based on atmospheric water deficits (AWDs). Fifteen years of daily precipitation, air temperature, and soil moisture measurements for eight locations across Oklahoma were used to calculate the probability (P) of water deficits sufficient to cause plant water stress for each day of the growing season. For the SWD method, the drought threshold was set at 50% depletion of the soil’s total available water capacity. For the AWD method, the threshold was a 7‐d cumulative AWD of 50 mm. Values of AWD were similar to calculated SWD for the 0‐ to 40‐cm soil layer in the spring; however, AWD values seldom reached the drought threshold. Thus, drought P values calculated by the AWD method were unreasonably low and consistently lower than P estimated by the SWD method. The AWD method showed greater agreement with the SWD method when 37 mm was used as the AWD threshold or when the original 50‐mm threshold was applied for a 15‐d cumulative AWD. The new SWD method gave plausible and consistent results when applied to both the 0‐ to 40‐ and 0‐ to 80‐cm soil layers and should be utilized when long‐term soil moisture data are available.

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Maize (Zea mays ) seed orientation at planting can influence emerging leaf angle. If leaf angle were consistent among plants without leaf overlap, large numbers of these bilaterally symmetrical plants could be arranged to optimize light interception and possibly increase grain yields or maintain grain yield with a lower population. The objectives were to evaluate the effect of seed orientation in soil on the angle of maize leaves relative to the planted row and on emergence rate. Seeds were planted 2.5 cm deep in diverse combinations of flat, cotyledon down, cotyledon up, on their side, radicle up and radicle down. Each seed orientation was repeated 10 times. Data on days to emergence and leaf angle were collected. In three experiments, maize seeds planted flat with the cotyledon up resulted in homogenous and faster emergence, and maize leaves aligned perpendicular to the direction of the maize row. Similar results were achieved with maize seeds planted parallel to the row with the radicle down. Random placement of maize seeds resulted in random orientation of maize leaves and lower emergence rates. The effects of controlled leaf geometry could facilitate planting higher populations with the potential for increasing grain yield and/or allow the maintenance of grain yields while reducing seed rates.