Agriculture & Biology
corn
100%
nitrogen
50%
alfalfa
45%
nitrogen fertilizers
43%
soil
40%
grain yield
40%
tillage
34%
no-tillage
31%
cropping systems
29%
China
26%
crops
25%
plateaus
25%
water use efficiency
24%
intercropping
23%
mulching
21%
wheat
21%
loess
20%
soybeans
19%
nitrates
19%
Zea mays
17%
plastics
17%
Vicia sativa subsp. sativa
15%
peas
15%
forage
15%
arid zones
14%
Ambrosia trifida
14%
conventional tillage
14%
nutrient use efficiency
14%
stover
13%
Corn Belt region
13%
planting date
12%
plant density
12%
urea
11%
water stress
11%
winter wheat
10%
cultivars
10%
nitrous oxide production
10%
weather
10%
straw
9%
fertilizers
9%
sowing
9%
dry environmental conditions
9%
legumes
9%
nitrous oxide
9%
leaves
9%
potatoes
9%
Medicago sativa
8%
spring wheat
8%
planting
8%
Earth & Environmental Sciences
maize
46%
nitrogen
32%
wheat
30%
mulching
22%
tillage
19%
plastic
19%
soil
19%
crop
19%
water use efficiency
18%
intercropping
16%
forage
14%
alfalfa
13%
fertilizer
12%
loess
12%
nitrous oxide
12%
zero tillage
12%
nitrate
11%
urea
11%
productivity
9%
straw
9%
bioreactor
9%
irrigation
9%
yield response
9%
cropping practice
9%
arid region
8%
crop rotation
8%
rate
8%
mulch
7%
soil water
7%
cultivar
6%
removal
6%
semiarid region
6%
economics
5%
fertilizer application
5%
biochar
5%
weather
5%
meta-analysis
5%
air temperature
5%
soybean
5%
surplus
5%
winter
5%
nitrite
5%
sowing
5%
nitrification
5%
footprint
5%
Medicine & Life Sciences
Soil
33%
Zea mays
29%
Brassica rapa
19%
Nitrogen
17%
Brassica napus
17%
Soybeans
13%
Triticum
12%
Capsicum
12%
Vicia sativa
11%
ammonium nitrate
10%
Nitrification
9%
Fertilizers
9%
Nitrites
9%
Photosynthesis
8%
Fertilization
8%
Ammonia
7%
Temperature
7%
Urea
7%
Chloroplasts
7%
Solanum tuberosum
7%
Ammonium Compounds
7%
Cold-Shock Response
6%
Droughts
6%
Nutrients
6%
biochar
6%
Weather
5%
Cadmium
5%
Genes
5%
Cold Temperature
5%
China
5%
Chive
5%
Plastics
5%