Shin Deguchi

Evaluation of feeding value of forage soybean silage as a substitute for wheat bran in sheep

Twelve sheep were used in a 3 × 3 Latin square design to evaluate the effect of substituting wheat bran with forage soybean silage in the diet on apparent digestibility and nitrogen balance. Forage soybean (Glycine max (L.) Merrill) was cultivated in a no-till, no-herbicide cropping system with Italian ryegrass (Lolium multiflorum Lam.) as a living mulch. Forage soybean and Italian ryegrass were wilted and ensiled in round bales without additives, respectively. The experimental diets were based on corn silage supplemented with protein sources (tow silages or wheat bran). The crude protein and the acid detergent insoluble protein contents of forage soybean silage were the highest among the protein sources. The apparent digestibility of crude protein and the nitrogen balance did not significantly differ among the diets. In addition, the phytoestrogen content of forage soybean silage was below the level at which animal reproductive performance would be negatively affected. These results suggest that forage soybean silage has comparable feeding value to wheat bran, and can be given at an inclusion level of 17% (dry matter basis) as an alternative protein source to wheat bran without adverse effects on digestion or nitrogen balance in sheep fed a corn silage-based diet.

Living Mulch with White Clover Improves Phosphorus Nutrition of Maize of Early Growth Stage

We examined the effect of a living mulch with white clover on the growth of maize in an Andisol. Maize was grown using a living mulch without fertilizer application, or by conventional cultivation with or without fertilizer application. Although the living mulch did not affect the amount of available phosphate in soil, the phosphorus concentration of maize shoots increased due to the living mulch compared with conventional cultivation without fertilizer application. Arbuscular mycorrhizal (AM) colonization of maize roots was higher with the living mulch than with conventional cultivation. These results suggested that a living mulch with white clover enhanced the phosphorus uptake by maize through AM colonization.

Arbuscular mycorrhizal colonization increases phosphorus uptake and growth of corn in a white clover living mulch system

White clover (Trifolium repens L.) living mulch, a cover crop cultivation system, has been shown to improve phosphorus (P) nutrition and increase the yield and arbuscular mycorrhizal colonization rate of the main crop without inoculation of fungi. However, it remains unclear whether the P uptake of corn (Zea mays L.) in living mulch is promoted directly by arbuscular mycorrhizal colonization. We performed a pot experiment to test the hypothesis that living mulch increases the P uptake of corn by promoting arbuscular mycorrhizal colonization. The experimental design was a 2 × 2 factorial arrangement using fungicide treatment (fungicide application or no fungicide application) and cropping system (living mulch or no mulch). The fungicide dazomet was used to inhibit arbuscular mycorrhizal colonization. Without fungicide application, the P concentration and dry weight of the corn shoots were greater in the living mulch than in the no mulch treatment, indicating that living mulch improved the P nutrition and growth of corn. Fungicide application in living mulch, however, decreased the P concentration, dry weight of corn shoots, and arbuscular mycorrhizal colonization compared with no fungicide application. These results suggest that living mulch increases the P uptake of the main crop by promoting arbuscular mycorrhizal colonization by indigenous fungi.

Compost application increases the soil temperature on bare Andosol in a cool climate region

Abstract Soil temperature is an important factor influencing crop growth. Within limits, a higher soil temperature will promote crop growth, particularly in cool climates. The application of compost increases the soil temperature, probably by drying the soil surface, but the relationship between soil temperature and soil water remains unclear. We conducted pot and field experiments on a bare Andosol in a cool climate region. The pot experiment examined the effects of compost application on soil temperature and evaporation, and the field experiment examined the effects of the properties and amount of compost on soil temperature. Pots with compost had a higher soil temperature and less evaporation than pots without compost. The decrease in evaporation and the increase in soil temperature by compost application were significantly correlated. The field experiment included 15 treatments: 12 compost treatments (four types of compost × three levels) and three chemical fertilizer treatments (one type of fertilizer × three levels). There was a significant correlation between soil temperature and the dry weight of the applied compost. We conclude that compost application increases soil temperature by decreasing evaporation from the soil surface. In addition, soil temperature increases with increasing dry weight of the compost applied, regardless of the chemical properties.

White clover living mulch controlled only by mowing supplies nitrogen to corn

Abstract A field experiment was conducted to investigate the effects of white clover (Trifolium repens L.) living mulch controlled only by mowing on the nitrogen (N) nutrition and yield of silage corn (Zea mays L.). Eight treatments were tested: one living mulch treatment without N application and seven conventional cultivation treatments with different N applications (0–200 kg ha−1). White clover was sown in the living mulch treatment in August. The next May, white clover shoots in the living mulch treatment were clipped and left in the field. After tilling the conventional cultivation treatments, corn was sown. At the time when the corn was sown, the N uptake of the white clover shoots was 173 kg ha−1. Measurements at 40 days after the sowing of corn (40 DAS) revealed that the N concentration of corn shoots grown in the living mulch treatment was lower than that in the conventional cultivation treatment without N application. At harvest (123 DAS), compared with that in the conventional cultivation treatment without N application, the N uptake of corn shoots in the living mulch treatment increased by 31.8 kg ha−1. Based on the N uptake and the yield of corn, the fertilizer N equivalencies of living mulch were 62 and 70 kg ha−1 at harvest, respectively. These results indicate that living mulch controlled only by mowing increases the N uptake of corn and may reduce the N application required for corn production.

Potassium nutrient status of corn declined in white clover living mulch.

Abstract We conducted a field experiment to investigate the effects of white clover living mulch on potassium (K) nutrition and the yield of silage corn. We used a randomized block design with a 2 × 3 factorial arrangement of cropping system and K application treatments. The cropping system treatments were: (1) a white clover living mulch (LM) that had been established 10 months earlier, (2) conventional cultivation with no cover crop (CC). The K application treatments were: (1) no K application (K−), (2) K application at sowing of white clover (Kclover), (3) K application at sowing of corn (Kcorn). In the LM treatments, white clover was sown in August 2006. Corn was sown in June 2007. Before the corn was sown, the white clover shoots in the LM treatments were clipped. The three conventional cultivation treatments were then tilled and corn was sown in all treatments using a minimum tillage seeder. In the LM K) treatment, we observed symptoms of K deficiency in corn leaves on 23 July. At the silking stage of corn, the K and N contents of ear leaves in the LM treatments were significantly lower than those in the conventional cultivation treatments. In the LM K− treatment the K content of ear leaves was <1% and the yield of corn shoots was less than that recorded in the other treatments. Multiple regression analyses revealed that K was the nutrient most strongly related to corn yield. These results suggested that white clover LM declined the K nutrient status of corn and as a result decreased the yield of corn.