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Previously selected plants for improved lines of kleingrass (Panicum coloratumL.) were evaluated for growth and seed production characteristics. At the initiation of this test, 13 experimental synthetic varieties were available for chemical comparisons of forage quality. This study was conducted to determine if differences existed in percent of neutral detergent fiber (NDF) and NDF components within the available synthetic varieties of kleingrass. The effects of five stages of plant maturity on NDF and its components were also evaluated for each variety. Since kleingrass has an indeterminate type of growth form, plants collected as initial and regrowth forage were harvested when a certain percent of the seed on the most mature kleingrass tillers reached the soft dough stage, but prior to the time of seed maturation. Previously nonharvested cumulative forage was collected at the same chronological age as the regrowth forage. At each of the maturity‐stage dates, plant samples were separated into leaf laminae and stems. Each plant part was analyzed for its neutral detergent solubles:neutral detergent fiber ratio (NDS:NDF). The NDF was then sequentially partitioned into hemicelluloses (HEM), cellulose (CEL), lignin (LIG), and ash. The hemicelluloses were further divided into easily hydrolyzable (EHH) and difficulty hydrolyzable hemicelluloses (DHH). Kleingrass varieties differed in NDS:NDF and NDF components. Leaf:stem ratios ranged from 1:1 to 1:4. By harvesting at a morphological stage prior to seed maturation, the NDS: NDF ratio of leaves and stems in regrowth forage did not vary throughout the study period. Leaf laminae contained approximately 34% HEM and 24% CEL; whereas, stems contained approximately 34% HEM and 34% CEL. With advancing maturity, HEM of leaf laminae increased at the expense of CEL. However, the HEM: CEL ratio of stems remained at approximately 1:1 throughout the collection period. The EHH:DHH ratio changed significantly with plant age as percent EHH increased and DHH decreased. The percent of LIG in both leaves (3.2%) and stems (6.6%) changed with plant age but the buildup of LIG was greatest in stems. Acid‐insoluble ash was influenced by the stage of growth only in leaf laminae and the leaves, with an average of 2.4%, contained four to eight times more ash than did stem sections.

Recent studies have shown that differences in neutral detergent fiber:neutral detergent solubles ratios (NDF:NDS) exist within experimental synthetic varieties of kleingrass (Panicum coloratumL.), and those varieties which had the highest NDF content were genetically closely related. This investigation was initiated to determine if selected varieties which differed in NDF:NDS also differed in in vitroand in vivodigestibility. The relationships between NDF, components of NDF, and various NDF component ratios vs. in vitroand in vivodigestibility were also studied using three synthetic varieties harvested at four stages of plant growth. Initial and subsequent regrowth forage was harvested as a certain percent of seed reached the soft dough stage, but before seed maturation had occurred. Cumulative growth forage was collected at the same chronological time as the final regrowth harvest date. At each harvest date, analyses were obtained for in vivodigestible dry matter (DDM), in vitrotrue digestible dry matter (IVDDM), neutral detergent fiber (NDF), digestibility of NDF (DNDF), and NDF components (hemicelluloses, cellulose, lignin, and ash). Percent DDM, IVDDM, and DNDF declined from 62, 74, and 60%, respectively, to 51, 65, and 47%, respectively, with plant maturity. NDF increased from 64% to 71% with plant age and accounted for approximately 92% (r = −0.96**) of the variability associated with DDM. The regression of DDM vs. DNDF resulted in a positive relationship (r = 0.99**). NDF vs. DNDF gave a highly significant negative relationship (r = −0.93**). Cellulose, lignin, and lignin:acid detergent fiber ratio were negatively related to DNDF; whereas, hemicellulose:NDF and hemicelluloses:cellulose ratios were positively related to DNDF. Regression with IVDDM and NDF components and component ratios were of the same magnitude as those relationships with DDM. The level of NDF showed a closer relationship to its digestibility than did any NDF component ratio with DNDF. NDF and DDM showed no difference between varieties, but the IVDMM analyses proved one of the varieties to be superior to the other two.

Studies were conducted to determine the influence of N, P, and K fertilization and different stages of growth on the nutritional quality of kleingrass (Panicum coloratumL.) forage. Nitrogen rates ranged from 28 to 560 kg/ha with additions of 24 and 73 kg/ha P, and 0, 46, and 139 kg/ha K. Leaf‐stem separations were made at each harvest date and cellular (neutral detergent extract; NDE) and cell wall constituents (neutral detergent fiber; NDF) were determined on the plant parts. The NDF fraction was then sequentially partitioned into hemicellulose, cellulose, lignin, and ash. Levels of N or P were significantly negatively correlated with percent NDF of leaf laminae. Chemical components of stem fiber were not altered by fertility levels. On a whole‐plant basis percent NDF was reduced about 5 percentage units by additions of N. Percent NDF in leaves and stems increased with chronological and morphological age. The holocellulose content of leaves remained relatively constant throughout the study period; with advancing maaturity, however, the hemicellulose fraction accounted for a greater portion of the NDF than did cellulose. The hemicellulose:cellulose ratio increased to approximately 1.7:1 in leaves, but remained at 1:1 in stems with increasing maturity. The leaves apparently had more influence on decreasing NDF of the whole plant under fertilization, whereas, stems were the dominant factors involved in increasing NDF of the whole plant with advancing maturity.

A field experiment was conducted to determine recovery efficiencies for applied N, P, and K under a system of total removal of forage (Cynodon dactylonL. Pers. ‘Coastal’) over a 3‐year period. Ammonium nitrate, (NH2)2CO, and (NH4)2SO4were each applied in split applications of 0, 280, 560, and 840 kg N/ha each season. Soil levels of total N, chemically extractable P, and K were monitored each season. Results show that N recovery percentages ranged in the following order: (NH4)2SO4>NH4NO3> (NH2)2CO. Characteristic decreases in recoveries occurred with increasing N rates. Source effects on recovery efficiencies for P were as follows: NH4NO3⩾ (NH4)2SO4> (NH2)2CO. Average P recovery percentages for NH4NO3were 34, 46, and 52% for rates of 280, 560, and 840 kg N/ha, respectively. Plant recovery of applied K was greatest for (NH4)2SO4and lowest for (NH2)2CO. Average values for (NH4)2SO4were 108, 165, and 222% for the low, medium, and high rates of N, respectively. Ammonium sulfate gave greater accumulation of soil N with time than NH4NO3or (NH2)2CO while chemically extractable soil P and K were highest for NH4NO3.

The effect of two stocking rates on the recycling of N, P, and K was studied for 2 years on a Coastal bermudagrass [Cynodon dactylon(L.) Pers.] sward. Samples for chemical analysis were taken at 14‐day intervals. Available forage, forage yield, and forage consumption were estimated from samples taken at 2‐ to 4‐week intervals. Soil samples were taken prior to, during, and at termination of the grazing trial. Plant nutrient recycling on the high stocked pastures was approximately twice as great during the dry, 1969 season and about 10% higher during the 1970 season compared to that on the low stocked pastures. Recoveries of applied plant nutrients averaged over stocking rates were 84, 50, and 155% for N, P, and K, respectively, during 1969, and 180, 73, and 172% for N, P, and K, respectively, during 1970. There was a substantial soil accumulation of plant nutrients under both stocking rates with a considerable advantage in favor of the high stocked pastures. On the high stocked pastures, total soil N accumulation was slightly less than twofold, available soil P increased threefold, and available soil K increased more than twofold over the 2‐year period.